Removed control for Bison >= 2.6 and supported old syntax for '%define api.prefix', which is '%name-prefix'
travis: try with bison 2.5
add configure status, used variables
travis: add matrix, autotools, cmake
update readme, lower bison to 2.5+

* current version of Travis is bison 2.5
* it is broken with default 2.3 on the OS X
Changelog: bison tested with 2.5, 3.0.2

* requirement was 2.6+
Merge branch 'relax-bison-requirement'