Improved paragraph and block movement

Move Markdown block movement and marking commands to
C-M-{, C-M-}, and C-c M-h.

In their place, add syntax-aware Markdown paragraph movement commands:
M-{ (markdown-backward-paragraph),
M-} (markdown-forward-paragraph), and
M-h (markdown-mark-paragraph).

The "plain text block" movement commands introduced in development
since v2.2, which were not syntax-aware, have been removed.

These paragraph and block commands differ primarily in granularity,
with blocks being larger and containing multiple paragraphs.  Take
lists, for example: paragraph movement commands stop at each list item
while block commands move over entire lists.

This commit is related to GH-191.

CHANGES.md

@@ -139,10 +139,16 @@
         `markdown-mark-subtree` (<kbd>C-c C-M-h</kbd>) and
         `markdown-narrow-to-subtree` (<kbd>C-x n s</kbd>).
         ([GH-191][])
-    -   Add plain text block movement commands: <kbd>C-M-{</kbd>
-        (`markdown-beginning-of-text-block`) and <kbd>C-M-}</kbd>
-        (`markdown-end-of-text-block`).  To mark a plain text block,
-        use <kbd>C-c M-h</kbd> (`markdown-mark-text-block`).
+    -   Add syntax-aware Markdown paragraph movement commands:
+        <kbd>M-{</kbd> (`markdown-backward-paragraph`) and
+        <kbd>M-}</kbd> (`markdown-forward-paragraph`).  To mark a
+        paragraph, use <kbd>M-h</kbd> (`markdown-mark-paragraph`).
+        These move at a more granular level than the block movement
+        commands.  ([GH-191][])
+    -   The previous block movement and marking commands are now at
+        <kbd>C-M-{</kbd>, <kbd>C-M-}</kbd>, and <kbd>C-c M-h</kbd>.
+        In terms of lists, paragraph movement commands now stop at
+        each list item while block commands move over entire lists.
         ([GH-191][])
     -   Add `subtree` as a possible value for
         `markdown-reference-location` and
@@ -184,7 +190,7 @@
         `:package-version` tags.
     -   Better consistency of function names: predicate functions
         ending in `-p` shouldn't modify match data.
-    -   Generalize rebinding of block movement commands in case users
+    -   Generalize rebinding of paragraph movement commands in case users
         have customized `{forward,backward,mark}-paragraph` bindings.
     -   Adjust point so that it is left at beginning of setext
         headings in heading navigation commands.

README.md

@@ -467,18 +467,26 @@ keybindings by pressing <kbd>C-c C-h</kbd>.
     at the point.  Finally, <kbd>C-c C-u</kbd> will move up to a lower-level
     (higher precedence) visible heading.
 
-  * Movement by Markdown Blocks: <kbd>M-{</kbd> and <kbd>M-}</kbd>
-
-    These keys are usually bound to `forward-paragraph` and
-    `backward-paragraph`, but those built-in Emacs functions are
-    based on simple regular expressions and can fail in Markdown.
-    Blocks in `markdown-mode` are code blocks, blockquotes, list
-    items (which may contain other blocks), headings, horizontal
-    rules, or plain text paragraphs separated by whitespace.
-    Instead, they are bound to `markdown-forward-block` and
-    `markdown-backward-block`.  To mark or narrow to a block, you
-    can use <kbd>M-h</kbd> (`markdown-mark-block`) and <kbd>C-x n b</kbd>
-    (`markdown-narrow-to-block`).
+  * Movement by Markdown paragraph: <kbd>M-{</kbd>, <kbd>M-}</kbd>, and <kbd>M-h</kbd>
+
+    Paragraphs in `markdown-mode` are regular paragraphs,
+    paragraphs inside blockquotes, individual list items, headings,
+    etc.  These keys are usually bound to `forward-paragraph` and
+    `backward-paragraph`, but the built-in Emacs functions are
+    based on simple regular expressions that fail in Markdown
+    files.  Instead, they are bound to `markdown-forward-paragraph`
+    and `markdown-backward-paragraph`.  To mark a paragraph,
+    you can use <kbd>M-h</kbd> (`markdown-mark-paragraph`).
+
+  * Movement by Markdown block: <kbd>C-M-{</kbd>, <kbd>C-M-}</kbd>, and <kbd>C-c M-h</kbd>
+
+    Markdown blocks are regular paragraphs in many cases, but
+    contain many paragraphs in other cases: blocks are considered
+    to be entire lists, entire code blocks, and entire blockquotes.
+    To move backward one block use <kbd>C-M-{</kbd>
+    (`markdown-beginning-block`) and to move forward use <kbd>C-M-}</kbd>
+    (`markdown-end-of-block`).  To mark a block, use <kbd>C-c M-h</kbd>
+    (`markdown-mark-block`).
 
   * Movement by Defuns: <kbd>C-M-a</kbd>, <kbd>C-M-e</kbd>, and <kbd>C-M-h</kbd>
 
@@ -489,17 +497,6 @@ keybindings by pressing <kbd>C-c C-h</kbd>.
     to the end of the current or following defun, and <kbd>C-M-h</kbd> will
     put the region around the entire defun.
 
-  * Movement by Plain Text Blocks: <kbd>C-M-{</kbd>, <kbd>C-M-}</kbd>, and <kbd>C-c M-h</kbd>
-
-    While the block and defun movement commands respect Markdown
-    syntax, these commands simply move over whitespace-separated
-    plain text blocks without regard for the context.  You can use
-    these commands to move over entire lists, whitespace separated
-    segments of code, etc.  To move backward use <kbd>C-M-{</kbd>
-    (`markdown-beginning-of-text-block`) and to move forward use
-    <kbd>C-M-}</kbd> (`markdown-end-of-text-block`).  To mark a plain text
-    block, use <kbd>C-c M-h</kbd> (`markdown-mark-text-block`).
-
   * Miscellaneous Commands:
 
     When the [`edit-indirect`][ei] package is installed, <kbd>C-c </kbd>`