Array: refactored code and improved readability.

* get() no longer calls GC.addRoot(), because it tells
  the GC to keep the memory alive even with no references.
* Call onOutOfMemoryError() on lack of memory.
SettingsLoader: use Array(256) as a buffer.
Lexer: refactored code to make use of In().

* Moved members p and end to the top (most accessed.)
common: added two tests cases for In() and Set().