lua console.

wal/big tests worked with system spaces which had no system spaces
data. Which is good. But not the way it is supposed to work.

Conflicts:
	src/box/lua/box.lua

Remove a piece of dead code which made select_range() and
select_reverse_range() extremely inefficient (a new iterator
instance for each tuple) and confusing.

box.index.iterator() creates a closure which is sufficient
to produce all iteration results. Use of index:next()
was apparently left by some tricky merge.

dostring() from init.lua, remove space declaration from a configs

and the new data dictionary

for proper yaml output

Fix a bug with missing tonumber() in space:select_range().

Fix bug: 'When server unexpectedly goes down Testing system waits while pid-file is deleted, but he wont'

fix end-of-document marker for multi documents return.

Add replace_if_exists as a stock method of a space.

Patch lua-yaml emitter to add \n after ---.

Still some issues with Lua console to fix, but transfer
big/sql.test to the new data dictionary at least.

Fix a bug found in the process that when altering an index
from unique to non unique the index is not rebuilt.

Remove 'lua ' prefix from schema_erase/schema_fill classes.