Rename project from Lua to Lush

Binary is now 'lush', library is 'liblush.a'. Version banner shows
"Lush 0.1.0" with original Lua copyright preserved. Adds LUSH_VERSION
defines and _LUSH_VERSION global. Internal C API names, env vars, and
default paths are unchanged for upstream compatibility.

testes/all.lua

@@ -1,4 +1,4 @@
-#!../lua
+#!../lush
 -- $Id: testes/all.lua $
 -- See Copyright Notice in file lua.h