precore: added working directory scoping, helpers, and simplified configs.
precore: added working directory scoping, helpers, and simplified configs.

precore:
	added config properties;
	added push_wd(), pop_wd(), and wd_scoped();
	added path_relative() and helpers();
	added make_config_scoped();
	renamed "init" config sub-block to "general";
	renamed configs to use precore as a prefix;
	ensure applied config table retains order with nested application;
	added append_config() and append_config_scoped();
	added include();
	simplified substitution table stuff: ROOT is defined at init and nowhere else;
	added env();
	nil state before init(), set state on init();
	added print_debug();
	replaced precore-env-root and precore-env-project-name with precore.env-common.


komiga/precore