Spirit V2.4.1

Fixed broken Spirit.Qi debugging facilities for optional attributes.
The Spirit.Qi auto parsers and Spirit.Karma auto generators will now properly work with signed char and unsigned char as well.
Fixed a problem in the multi_pass fixed_queue policy.
Enabled proper modifier handling for the skip directive.
Fixed a floating point formating problem in Karma (TRAC#4742).
Fixed a problem in repeat[], which caused the first iterator not to be reset on certain parsing failures (see Stack Overflow).