alternative take on error handling

- errors are now simply printed allowing more errors at time
- new ErrorHandler class
print position of error in file

- TreeNode has now a position field
- node positions are set in ASTBuilder
- positions are parsed and printed by ErrorHandler
clean up mess

- remove commented-out code
- remove obsolete exceptions
Merge branch 'master' into errorAlt

Conflicts:
	src/com/lolcode/tree/AstBuilder.java
close issue #9, fix tests, code cleanup

- case label overriding is now reported as a warning
- function test fix(wrong arguments count error)
- remove empty if blocks from ASTBuilder