Sort error messages by line number

[GoogleCodeExporter]

Currently error messages are reported in the order they appear in byte code. 
Unfortunaetly with synthetic methods like used for closures or access$X stuff, 
the methods may come later in byte code, so those synthetics are listed after 
other failures, although line number is lower.

The fix would be to buffer the error messages and sort them by line number 
before output. This would also allow to make them accessible in a more 
structured way from code.

Original issue reported on code.google.com by uwe.h.schindler on 27 Sep 2013 at 9:24