Drastically performance increase of isAllowed-method

Dr. Sql has reduced complexity of isAllowed-method from 4+2n (with n
inherited roles_names) to 1 (ONE!) database query.
Should work on all nearly SQL-99 databases.
Fixed errors: PHP < 5.3 compat, Whitespace eof'

LOLWUT:
Build Error because of whitespace at end of file? Shouldn't be a problem
but here's the fix.
Just make travis happy...

Just make travis happy...
Fix: if GC not already triggered, session valid

The GC will be triggered randomly based on gc.divisor-values etc... if
you have low traffic on your page, the gc won't be executed in a
continous manner, so that the session will be valid, even if it's
lifetime is more than "maxlifetime".

The fix checks condition even in read-out of sessions.
Optimize session.write from three to one sql-statement
Revert "Optimize session.write from three to one sql-statement"

This reverts commit 578263e87f5f523cf2a7568b84499d0cd90cd58d.
Merge pull request #192 from theolymp/master

Drastically performance increase of isAllowed-method