1) Make memory counters aggregated.
2) Add attachment pool and allocate appropriate resources out of this pool.
3) Always release attachments explicitly (via destructor).
4) Always delete user requests prior to attachment deletion.
5) Introduce memory usage counters per every monitoring object.
6) Misc refactoring.
Some pieces are still incomplete (although everything basically works), but I'd like to get feedback and testing sooner rather than later.
and CORE-1079: Every attach of fbclient/fbembed library leaks 64KB of memory
To do it:
- created new template GlobalPtr, controlling access to destructors of global objects.
- applied it to global objects.
Also some related cleanup.
