2.5.0

This release brings again big performance improvements (thanks @stof for the excellent work).

v2.5 is 3.5 times faster than v2.4 and 11 times faster than v2.3!

Here a list of the changes:

• #162, #161, #155, #154, #153, #151: performance improvements
• #156: fixed typos
• #160: adopt and enforce code style
• #159: remove deprecated php unit base test case
• #150: backport changes from old master branch