Core changes:plugin manager merged in trunk , stored procedures speedup in 2.5.1

Dimitry fixed one bug with stored procedures slowdown in some cases :Tuned the code a little in order to avoid redundant retrievals. As a side effect, it downgrades three-way joins to two-way ones, thus helping the optimizer to choose a good plan in the worst (zero selectivity) cases. This should resolve CORE-2933 (Very slow execution of a script that creates a lot of metadata) and CORE-3237 (Slow compilation of stored procedures) without tweaking the optimizer constants.

New plugin manager was committed to trunk. Use it for all types of plugins.

Alex Peshkoff Fixed binary packages build. No more CS/SS difference. No more linux RPMs on SF (now they are created on each distro anyway)
Another interesting bug fixed in the future 2.5.1 is CORE-2756 :substring from timestamp – unexpected result