ESP config memory leak

[mincrmatt12]

Due to an oversight in the config parser generator, string members inside of objects are not freed when reloading the configuration. This causes memory leaks when new configurations are downloaded from the webui/cfgserver.

Current solution will be to replace all global unmanaged char * with a destructable config::string_t. This should also let the sim store default/non-default tracking flags without imposing memory penalties on the actual device to emulate the current behaviour of checking which region of memory the pointer is in.