Extend the Lua hook mechanism to capture assert failures and unprotected calls

[TerryE]

@pjsg has proposed a very specific implementation of an unprotect call handler, which I feel is an unnecessary imposition on Lua developers in general. However, it seems reasonable to ask for some standard mechanism for hooking into this for purposes of debugging. Lua already has a standard API exposed for this in the form of the lua_sethook() and related calls.

I suggest that we introduce the following API constants LUA_MASKUNPROTCALL and LUA_MASKASSERT into the core code so that the lua_sethook() API call can be used to establish hooks for these events which the extra logic to implement them. Developers are then free to set these hooks with their own custom code, and Phlip can then develop his own debug library should he wish to without imposing this implementation on all developers who wish to use the nodeMCU firmware.

[TerryE]

I feel that #1119 has really superseded this, so I will close this one -- especially as it has received no comments or interest.