Changed a lot (too much)

Probably should not have changed so much in one commit. Not so familiar
with GitHub conventions/good habits.

Add APIKeysLocal to compile list again,
refigure requests to use ShareX's native POST/GET,
add a few error handlers,
clean up push URL return code,
rename PushbulletDevice properties,
remove permanent "Hide Characters" setting (now it does that by default;
user must uncheck it to see characters),
add intCurrentDevice to PushbulletSettings (to be the index of
PushbulletDeviceList),
Add variable EncodedAPIKey for use in the header of requests

I am really horrible at this