Rasterize all available characters

[Yanrishatum]

Request by Trethaller;
When charset is not present in config - render all available characters in the fonts.
Implementation specifics:
Need to fetch list of all characters present in the font file via ttf library on C side, pack into bytes and return to Haxe via Ammer.
Short-term solution:
Add an everything alias that covers all official unicode blocks.

[Yanrishatum]

Short-term solution is present, but is far from being optimal.