Allow overriding user dir with MINICOIN_USER_DIR
Leaving config files and runtime/caches in a non-dotfile directory in ~ is a bit uncommon. Allow the user to override this to e.g. ~/.minicoin via MINICOIN_USER_DIR
Leaving config files and runtime/caches in a non-dotfile directory in ~ is a bit uncommon. Allow the user to override this to e.g. ~/.minicoin via MINICOIN_USER_DIR