Fixing greedy digits lookup in animation sprites file paths

Fixes quinton-ashley#197 . This is a tiny mergeable variant of PR https://github.com/molleindustria/p5.play/pull/175 which covers other things.

lib/p5.play.js

@@ -3443,11 +3443,15 @@ function Animation(pInst) {
       for (i = from.length-4; i >= 0; i--) {
         if(from.charAt(i) >= '0' && from.charAt(i) <= '9')
           digits1++;
+        else
+          break;
       }
 
       for (i = to.length-4; i >= 0; i--) {
         if(to.charAt(i) >= '0' && to.charAt(i) <= '9')
           digits2++;
+        else
+          break;
       }
 
       var prefix1 = from.substring(0, from.length-(4+digits1));