Map text improvements

[ArthurBeaulieu]

Don't limit char count in different texts (doesn't mean 1M char would behave correctly)
Auto compute font-size according to char number so it always display perfectly on the poster
For each editable text :

• Offer a gear icon, to open a font modal ;

• Font modal must provide several, open source, font, mixed serif/sans-serif, fun/strict

• Bonus point, hot font loading from user dropped TTF/WOFF

• propose several fonts for texts (individual to each text input)

• font size related to char count

• no max charcount, with wartning when overflowing