[GURPS] Somes fixes to the GURPS character sheet

Hi there, I took the freedom to fixe some issues with the GURPS character sheet and made a pull request since it had not been updated in a year now. Fixed attributes not updating properly because of unintended use of _max field. Fixed lifting box calculations. Fixed encumbrance calculations. Minor correction to the swing damage progression in the pop-up. I hope this will help.

Typically, once the code is on Github, its open to the public. Etiquette dicates that you let the author know & give him/her/it a chance to fix it, but other wise, go ahead and make the changes.  

has this been updated I am in the beginning stages of planning a GURPS campaign. Id like a very automated sheet. 

Hey,  I'm the original author of the _mutonized sheet but don't have time & will to keep it updated so yea man, go for it and feel free to own it as you will. If there are problems because the roll20 team doesn't handle duplicates or multi sheets too well after pull requests, feel free to contact me about it, send changes over or point them out to this thread. Enjoy :) G.

Ok, thanks. You did some great work.