Add keywords extension
added offline error handling for rules
impemented rule %= operator
Merge branch 'develop' of https://github.com/boostorg/spirit into feature/x3_keywords
Ported calc5 to X3 (Same as Calc4, this time, we'll incorporate debugging support, plus error handling and reporting).
fixes #5872
wrong underscore crept in
added on_sucess handler (complements on_error)
use enum class for error_handler_result
action should be in core, not auxilary
added x3::ast and x3::forward_ast (specialized versions of boost::variant and boost::recursive_wrapper)
improved variant interface
variant should be named variant. nothing else.
date changes
ported calc6 to x3
Updated tests to catch bug in tst_map
Fixed iterator rollback bug in tst_map
Merge pull request #11 from vtnerd/bugfix/tst_map

Bugfix/tst map
Merge branch 'develop' of https://github.com/boostorg/spirit into develop