Preliminary lexer and compiler
Add Token::setTypeIfNone()
Duplicate field token if a T_FIELD_VALUE follows T_FIELD_WEIGHT.

Simplifies the compiler (drop of a global var) at cost of a slightly
more complicated lexer
Add Token::getName() to get the token name from an int.
Add search field selector with @
Let lexer do more checking
Add escape character to lexer
Add lexer test
Fix starting position of recycled tokens
Compiler wraps QueryBuilder, add restrictions
Add documentation for QueryParser
Merge pull request #4 from vierbergenlars/query-parser

Add QueryParser