Allow LUACMSGPACK_MAX_NESTING to be set by CPP
Add tests for more edge cases

The 0xFFFFFFFF test can potentially fail on 32 bit systems if
our internal conversions are casting to wrong Lua types.
lua_Integer != lua_Number
Allow forcing 32 bit builds on 64 bit platforms
Update CI to test against 5.3.0 beta

5.3.0-work2 has been obsoleted by the newer 5.3.0-beta

This testing infrastructure is taken from:
https://github.com/moteus/lua-vararg/tree/246dc3126dd66935a020a0a26c165ceb035268e5/.travis
Fix 64 bit integer processing on 32 bit platforms

This is the solution to mattsta/lua-cmsgpack#4 but rewritten
to use compile-time pointer size determination.
5.3 compat: short functions to long functions

checkint -> checkinteger
optint -> optinteger

Also removes `< 503` check for creating pushunsigned.

Older lua versions had redundant functions, but one with a shorter
name than the other.  Newer Lua versions only retain the long version.

one is an alias of the other, but one was removed in 5.3+, so it's
better to use the common function across all versions.
Merge remote-tracking branch 'upstream/add-streaming-and-refactor-and-tests' into add-streaming-and-refactor-and-tests

Conflicts:
	lua_cmsgpack.c
	test.lua
Fix. test for pack nothing.