bigtwo: coffee.vrock released

here's 'vrock' that was delayed for a long time as i was stuck with other stuffs. the note worthy user visible changes are listed below... the source tarball is already out there, while pre-compiled binary packages shall be available pretty soon. [update: a linux binary package is available]

[vrock]
o [en] added game error messages
o [en] added basic game engine error reporting
o [en] added optional game rules support
o [en] added optional rule "no_threecarder"
o [en] added optional rule "anything_first"
o [ai] added handler for (not so obvious) single-carder win
o [ai] refined high card plays handling