First version of expanded token limits

[Jordach]

1500 total tokens, on 24GB cards. Plans are to dynamically change the number of allotted tokens based on batch size.

No user input is required for the token limit expansion.

If a batch of images contains more than 1500, it's truncated to size. Due to the shifting nature of memory usage, memory is cleared every 100 steps with a second through pass every 250 steps. May need adjusting for long term brewing, but has been stable for 42 hours without stoppage.

[devilismyfriend]

can you change the code so the extended mode will be presented as an option to the user rather than the default?

[Jordach]

Done and dusted.