Blender Git Loki

Added a new notifyer, NC_SPACE_CHANGED, to signal an editor that
replaces another so it can do updates (e.g. dopesheet editor can
sync channel selection).

Also coded a simple optimization for allocating small objects,
based on mempools. It's #ifdef'd out, you can enabled it by
defining OPTIMIZE_SMALL_BLOCKS (e.g. adding -DDOPTIMIZE_SMALL_BLOCKS to
your compiler flags).

We suffer from a great deal of performance loss from the system allocator
(vgroups, ghash, edgehash, the singly-linked list implementation in blenlib,
editmesh, and likely a great many areas I'm forgetting), and this is the
common solution for handling the many-small-objects problem. It's not
really production-ready yet (it's long-term memory consequencers need to
be profiled first, and the implementation tweaked as necassary), but for
people on systems with slow system allocators it's worth trying.

Note that since this creates a guardedalloc<->blenlib link, the build systems
need to be updated accordingly (I've already done this for scons, though I'm
not sure if the player builds).