* NEW: Added Key static class containing key constants
* NEW: Buffered property in Window class to allow buffered output
* NEW: Refresh method in Window class to produce output if Buffered property
was set
* NEW: Flush method in Window class to clear the input queue
* NEW: Ask method in Window class to prompt the user for specific keys
* NEW: PrintCenter method in Window class to print text in the centre of the
screen
* NEW: Window array accessors now used to change character attributes
* OPT: Standard input is watched only once
* BUG: Inserted missing return statement when reading Window.Border
git-svn-id: svn://localhost/gambas/trunk@4627 867c0c6c-44f3-4631-809d-bfa615b0a4ec
