also various fixes/cleanup to main

one important fix to avoid segfaults to to an extra pop in
lua_extension loading, then consolidated the loading mechanism and
added a library for easy data structure inspection

first extension is lua-schema to be able to have declarative scripts
with automatic type checking of data structures

further patches to LUA to expose functions and updates to the
documentation and to the header inclusions. now all new libraries
added in zenroom reside inside lua_functions.

the bindings are still WIP

now takes an extra DATA global string from stdin and loads
a special KEYS global string from -k on commandline.
The REPL is engineered to not brittle (parallel init of sanbox)

added linenoise to handle input and soon add completion etc.
still WIP as this doesn't prints stdout ATM.

copied over in luazen on build

this will obsolete use of frozen in favor of parsing inside lua