Update strings.js

update new strings
Cleaned up the preferences ids
Fixed forgotten id
Added Localisation for the Loading... message
Added preferences migration code
Exported handleClientIdChange
Fixing issue #2923 - Getting mode from file extension won't always work
Fixing issue #2923 - Getting mode from file extension won't always work
Merge branch 'markmurphy/issue-2923' of github.com:MarkMurphy/brackets into markmurphy/issue-2923

Conflicts:
	src/language/LanguageManager.js
add missing comma
Final migration handling implemented
Reverted change in PreferencesManager
Refactoring "getLanguageFromFilePath" to "getLanguageFromPath". Reverted language.name back to language._name

Removed typescript and makefile declarations from languages.json. Will save for a later pull-request.
Cleaned up whitespaces and indents
Update getKeyBindings()
Only provide hints for JavaScript files (and not JavaScript within HTML files), and cleanup stale session objects when switching to non-hintable files.
Fixed errors raised by KeyBindingManager unit test
Updated addBinding()
Updated _addBinding()
Add boss variable back in