Fmt, Clippy, CI to match other georust proj

Please rename the primary branch to `main` for consistency.

Similar to other georust projects, make CI:
* go through additional fmt and clippy validation
* run on pull requests, but ignore non-standard branches (it is usually easier to submit PRs from personal forks, but some maintainers may do it from the primary repo)
* run fmt and clippy
* add `TileJSONBuilder::default()`
* ignore intellij files

Minor cleanup:
* use `.to_string()` everywhere for consistency
* use Self when possible

Also, get rid of the custom `cargo-all-features` as it is not really needed, so using the KISS principle :)

Author: nyurik

.github/workflows/rust.yml

@@ -1,10 +1,45 @@
-on: push
+on:
+  push:
+    branches:
+      - main
+      - staging
+      - trying
+      - release/**
+  pull_request:
+  schedule: [cron: "45 6 * * *"]
+
+env:
+  RUST_TOOLCHAIN: stable
+  TOOLCHAIN_PROFILE: default
+
 name: Run tests
 jobs:
-  build_and_test:
+  lints:
+    name: Run cargo fmt and cargo clippy
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - run: cargo install cargo-all-features
-      - run: cargo build-all-features --verbose
-      - run: cargo test-all-features --verbose
+      - name: Checkout sources
+        uses: actions/checkout@v2
+      - name: Install toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          profile: ${{ env.TOOLCHAIN_PROFILE }}
+          toolchain: ${{ env.RUST_TOOLCHAIN }}
+          override: true
+          components: rustfmt, clippy
+      - name: Cache
+        uses: Swatinem/rust-cache@v1
+      - name: Run cargo fmt
+        uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check
+      - name: Run cargo clippy
+        uses: actions-rs/cargo@v1
+        with:
+          command: clippy
+          args: -- -D warnings
+      - name: Run cargo test
+        uses: actions-rs/cargo@v1
+        with:
+          command: test

.gitignore

@@ -1,3 +1,4 @@
 /target/
 **/*.rs.bk
 Cargo.lock
+.idea

CHANGELOG.md

@@ -1,3 +1,7 @@
+### Unreleased
+
+* for consistency, add `TileJSONBuilder::default()` - same as `::new()`
+
 <a name="v0.2.4"></a>
 ### v0.2.4 (2021-10-11)