Make Cmdline modules case insensitive

[HebaruSan]

Previously, Cmdline users had to type the exact capitalization of each mod identifier in the install, remove, and upgrade commands. This pull request adds a lookup step to convert "incorrectly"-capitalized identifiers to their correct capitalization, based on what is indexed in the registry. This allows users to type any capitalization they like as long as the letters are all the same.

Before:

$ mono ckan.exe install astroGATOR
Module astroGATOR required but it is not listed in the index, or not available for your version of KSP.
If you're lucky, you can do a `ckan update` and try again.
Try `ckan install --no-recommends` to skip installation of recommended modules.

After:

$ mono ckan.exe install astroGATOR
About to install...

 * Astrogator v0.7.8(cached)

Continue? [Y/n] 

The identifier=version format code is refactored slightly to create a reusable/shared compiled Regex object, then used in CkanModule.FromIDandVersion as well as the new lookup code.

Fixes #889.