Merge pull request #13 from SaveTheRbtz/master

Misc and portability fixes
Merge pull request #14 from SaveTheRbtz/master

Faster stats, Adaptive mutexes and Coverity report fixes
v0.18.6
Merge branch 'devel'
stat: added notes about atomicity of update
index: allocate index blocks in contious region

This decreases allocator pressure on start and decreases memory
fragmentation.

This also stepping stone for removal of index blocks tree which will
further reduce memory footprint and possibly increase speed.