fix($parse): allow most latin letters as identifiers

Angular will today throw an execption if binding using an expression with extended latin letters as JSON object properties. Eg if $scope.a = {"hellö": world"}, you cannot bind to {{a.hellö}} although this is valid JSON.
This fix allows most extended latin letters by adding three ranges of latin letters in the isIdent(ch) check.
It's a compromise:
- The division and multiplication sign split above ranges and are not allowed
- Some more latin letters exist, but they are spread out and hunting them one by one might be too costly
Two tests supporting above statements are included.

Closes #2174