[PATCH 0 of 3] simplify test-check-code

[Simon Heimberg]

[Patch 1] check all code in one run. This 2nd version should not run some tests
twice when the command line is split by xargs. And I hope it is portable.

[Patch 2] doing a rename instead of a 2nd copy looks better and a bit more optimised
(same as last time)

[Patch 3] print line numbers when running the test. The matching of the line 
number can be done by using glob. This should help to find failing lines quicker.