Move ome parsers of bg_misc.c to their own file

* The new file is bg_parse.c
* It has some macros to make the parsers a bit less verbose
* Add a BG_ReadWholeFile function in parse.c
Add strdup to bg_lib
Allocate dynamic strings and do not break on error
Do not use an error code

* Parsing of these files should never fail unless in dev
* Clean stuff
 Rename *ClassConfig* to *ClassModelConfig* to better name it
Move BG_ParseClassModelFile to bg_parse.c