Raised needed bison version.
Fixed warnings of bison 3.0.
Simplified parsing interface to bison output.
Removed unnecessary httpscan.h.
Added lexer state.
Added initial lexer transition to request or response first lines.
HTTP verbs are simplified by the lexer.
Lexer simplifies version parsing.
HTTP first line is now completely tokenized.
Simplified HTTP parser at all.
Header parsing is done in bisonwrapper.
Choose bison to enable parsing of special headers the first place.