Code review for tmp_spaces_1_6, fixes gh-34.

include/errcode.h

src/box/alter.cc

src/box/box.cc

src/box/box_lua_space.cc

src/box/key_def.h

src/box/lua/schema.lua

src/box/space.h

src/box/txn.cc

src/iproto.cc

test/box/alter_limits.result

test/box/lua.result

test/box/lua_misc.result

test/box/temp_spaces.result

test/box/temp_spaces.test.lua