lex: added int suffixes, fixed identifier bug, documented '-' brokenness
lex: added int suffixes, fixed identifier bug, documented '-' brokenness

- added identifierDone function which splits out the determination of whether the identifier is complete from the completion itself
- updated uses of finishIdentifier to reflect this change
- added integerDone function for similar purpose as identifierDone
- thoroughly documented possible state changes in integer scanning
- added handling for integer literal suffixes (l, u, lu/ul, no ll)
- replaced an instance of inPattern("0-9") with .isDigit()

- unary minus, binary minus, and minus assign are known to be broken
- running with test/literal_int.c currently causes a range violation

jgottula/jgcc