* Improved layout of addons menu.
* Disabled input for 5 tics after a console-touching enter key command on the menu, so that weird stuff doesn't happen.
* Added Add-on options.
* cv_addons_option - chooses save location. A little smaller in scope than the weird Default/HOME/SRB2/Custom thing for screenshots - now it's SRB2 Folder and Custom.
* cv_addons_folder - goes with Custom for above.
* cv_addons_md5 - chooses whether to identify files on the addons menu with name comparison only, or with checksum comparison as well (more intensive hence not default).
* cv_addons_showall - chooses whether to show just supported file extensions, or all
* Some minor other refactors.
Bad:
* Screenshot options menu crashes on access for some reason (to do with itemOn not being valid?????) looking into
https://gfycat.com/DizzyEnergeticCygnet
I will make it prettier.
(Also: stristr. Since the Windows (and others?) standard library doesn't have it for some reason, I modified code someone put on StackExchange as a stopgap; once I'm ready to get on IRC for the day, we'll discuss attribution/rewriting.)
* Named all the new functions/etc "Platter" instead of "NewList", to make maintenence easier and also because it sounds delicious.
* The code, as a whole, is much cleaner.
* Allows for multiple items under the same heading now, with highlights and spacing consistently handled.
* Allows for picking up where you left off between menus now (assuming the same map is available on multiple screens).
* Defined M_CanShowLevelInList in terms of the two compartmentalised functions cleaved from it, in order to ensure consistency and prevent code duplication.
