first attempts at more testing and comparison with SuperC
improve corner cases of lexer

- #ifdef +3
update infrastructure
correct terminology: parse -> lex
extract common interface for partial preprocessors: VALexer
start wrapping XtcPreprocessor and testing typechef tests with it
Merge branch 'master' into XtcIntegration
update infrastructure (followup to aefea1640d151fb5cd95e7c8528b8805951e37c5)
fix tostring behavior of XtcTokens
extend test case to check for dead code
change include directive
fix test case
use old tests again
document differences between xtc and typechef lexer
rewrite time measurement
use abstractToken instead of TokenWrapper also in CParser
Xtc Option in the Frontend

and major rewrite of how MacroContext/MacroFilter is used
tokenstats made optional
MacroFilter now used also for Xtc
simplify code