v0.50

Noticeable changes, except for various cleanup and "under-the-hood" improvements, include:

• fix sender name in termux-sms-list
• fix so that inbox message filtering works in termux-sms-list
• fix so that termux-camera-photo works (at least on Samsung devices)
• add the option for api scripts to communicate with termux-api through a unix socket, thereby decreasing execution time

Thanks to all the contributors!