Add filename/location info to ApplicableMethod

[ChrisJefferson]

Make ApplicableMethod show filename / location information.

Also add LocationFunc, a simple method to get filename:linenumber information for a function.

There are no tests, as they would inevitably have the current directory of GAP in.

[codecov-io]

Current coverage is 50.41% (diff: 8.33%)

Merging #1058 into master will decrease coverage by <.01%

@@             master      #1058   diff @@
==========================================
  Files           424        424          
  Lines        223027     223048    +21   
  Methods        3429       3429          
  Messages          0          0          
  Branches          0          0          
==========================================
+ Hits         112453     112454     +1   
- Misses       110574     110594    +20   
  Partials          0          0          

Powered by Codecov. Last update 14b7135...7eeec2f

[hulpke]

Nice!

[frankluebeck]

"In principle" nice!
But this produces many overlong lines because of the full paths. This makes the output difficult to read.

How about printing only the paths relative to the GAP root? (Similar to BrowseGapMethods from where you can also inspect the code.)

[ChrisJefferson]

In general, we could use shorter filenames in several places (such as in backtraces). There was a previous discussion on this and various people wanted the complete filename, even when it is under GAPROOT.