[beta] Improvements and 2.3 fixes

Additions:

• You can now drag and drop scripts from one project to another to copy.
• Added an “autocompletion delay” setting to code editor settings.
• Further expanded upon /// @hint and wrote a wiki page for it.

Improvements:

• Plugin list now uses little subcategories so that plugins can add controls into them.
• Added some preferences for Outline View.
• Added more auto-completion options (include keywords, don’t suggest snippets in strings/comments).
• Linter now accepts trailing commas in 2.3 object literals ({...}).
• Variable auto-completion now catches fields in object literals and non-top-level function declarations.
• Broken API files no longer cause GMEdit to fail (shows a popup instead).

Fixes:

• Fixed 2.3 script renaming not renaming the .gml file.
• Fixed GMEdit trying to open extra --args as files in general.
• Fixed object names in collision #events not highlighting accordingly.
• Fixed an error in 2.3 projects when inserting items out of order into an empty tree node.
• Fixed an error in 2.3 when creating the first asset of kind (thus there being no folder to put it in).
• Fixed newly created 2.3 scripts having .yy extension in resource tree metadata (otherwise fixed by reloading).
• Fixed /// @param inside 2.3 constructors overriding constructor params (#80.
• Fixed #import magic discarding new keyword in 2.3 projects in specific circumstances (#81).
• Fixed some things not working with nested local variables.
• Fixed bracket counting in 2.3 projects for code of kind var a = method({...}, function(){...}).
• Fixed asset variable definitions not working for 2.3 projects.