Eval: new functions keys_of_tags(), number_of_tags()
Eval: aliases for debug(): print(), println()
Eval: JOSM_search() for compatibility reasons
Eval: support function tr()
Support hsv() colors
Merge pull request #42 from plepe/42-eval-functions

More (JOSM) eval() functions

tr(), number_of_tags(), keys_of_tags(), print(), println(), JOSM_search(), but not hsb_color() => hsv() instead