Add Spanish translation and little changes to make localization easier.

Hey! I recently discovered Knave and your implementation for Foundry VTT and I really like it. Also the items illustration are very pretty.

I added a Spanish translation for the character and monster sheets and also make some minor changes to make localization work. Some changes were:

• fix a bug that caused that lack lines appear when the slots string was too large on the item slots header on the right column of the character sheet.
• add localize handlebars to the item sheets (Question. How do you use the for example spell sheet?)
• add missing string to the lang files
• add Spanish lang file
• add span tag around monster sheets attributes and width: max-content to prevent warping when translations string is too large (this only makes monster sheet a few pixels wider on the Spanish translation).

I submit this changes to you if you want to merge them into your system to make this translation available to the community. Also I'm starting t work in a translation of the compendium via a external module using foundry's Babele mod.

Thanks again for a great implementation of the system. Have you considered submitting to the oficial list?

PS: A thing I still can't figure out is how to localize the strings inside the JS files like "Rolling" when you roll dice. Any advice will be appreciated.