Add support for lookaheads

[MasseGuillaume]

// positive lookahead
passAndFail(".*\\.(?=log$).*$", "a.b.c.log", "a.b.c.log.")

// negative lookahead
passAndFail(".*\\.(?!log$).*$", "abc.logg", "abc.log")

// positive lookbehind
passAndFail(".*(?<=abc)\\.log$", "abc.log", "cde.log")

// negative lookbehind
passAndFail(".*(?<!abc)\\.log$", "cde.log", "abc.log")

// atomic group
pass("(?>a*)abb", "aaabb")
pass("(?>a*)bb", "aaabb")
pass("(?>a|aa)aabb", "aaabb")
pass("(?>aa|a)aabb", "aaabb")

// quantifiers over look ahead
passAndFail(".*(?<=abc)*\\.log$", "cde.log", "cde.log")