Prepare to remove sfscheme and switch to MessagePack.

Regression introduced by 9036eeeb

tuple is already referenced by phia_tx_write().
Regression by 1edaeabb

cur_L now properly updated if a Lua-C function raises an error

Prepare to remove phia_document.

Prepare to remove phia_document.

Conflicts:
	src/lib/small

Conflicts:
	test/box-tap/cfg.result
	test/box-tap/cfg.test.lua

 * deleted third_party/rb.h, fixed all included to src/lib/small/small/rb.h
 * rb: added external comparator with key, added custom members to struct rb.

* wallarm button alignment
* better action calls
* remove obsolete benchmarks & example

Conflicts:
	doc/sphinx/book/administration.rst

Conflicts:
	doc/sphinx/dev_guide/building_documentation.rst

Notable changes:
* fix for broken random()
* fix for JIT trace recording involving a pcall