VarDefs with types, correctly read from game.json and used for engine language

- VarDef types are restricted to string, float, integer and boolean
- VarDef names can be prefixed by '_' to indicate that they are reserved
- VarDef names prefixed by '_g_' are copied to/from subgames ("globals")
- Added I18N initialization in GameController using a LANGUAGE_VAR ("_g_lang")
- Added additional sanity checks to pseudo-properties parsing in i18n
Merge pull request #47 from manuel-freire/vardef-schema

VariableDefs read correctly from json; "lang" variable for game i18n
Renamed some constants. I18N loads default language in initialization
View controls in editor
Fixing Eclipse+Maven integration issues after upgrading the java-formater and license-checker plugins
Fixing formatting issues
Renaming:
 - GameController to GameLoop
 - EngineGameController to EngineGameLoop
 - gameController properties to gameLoop properties
Merge pull request #52 from imartinezortiz/engine_refactoring

Various renamings
Basic structure for the editor
Merge branch 'master' into editor
Added preferences to controller
Added menu and context menu widgets
Added preferences listeners; added recent games menu
Fix FactoryText
Added file chooser last folder preference
Recent files ignored the current game
Added change language action
Some refactoring in widgets. Added LinearLayout
Work in event model
Fix renamed class in libgdx