small updates on login, forgot and register pages
rename csv_format() to core_csv_format(), download() to core_download(), remove lib/fn_csv.php and lib/fn_download.php, move functions inside to lib/fn_core.php
rename gateway_get() to core_gateway_get() and move it to lib/fn_core.php, lib/fn_gateway.php removed
rename lang_get() to core_lang_get() and move it to lib/fn_core.php, lib/fn_lang.php removed
rename themes_get() to core_themes_get() and then move it to lib/fn_core.php, lib/fn_themes.php is not deleted
add $plugin_config as global config array, just like $core_config and $menu_config
remove global config array $plugin_config, insert them to $core_config['plugin']
re-structure function.php to load only active plugins, including themes, lang and gateway. this fixes icons as well
add an index marker in $menu_config for better menu sort