Fix/merge modules

[pape77]

Fixes Merge #204 !

@tonerdo So after playing a bit more around with my last change (which is already merged #204) , I realized I made a fuck-up because despite i was comparing by filename, you were already storing the keys for the Modules dictionary as complete paths in Coverage.cs.

This caused the comparison I modified in #204 to asume the keys for modules and Modules were the same. But i didn't change the values of these keys to be only the file name too, so they still had the complete path on it (and therefore, were different) .
As it tries to access the dictionary with the wrong key (asuming they were the same in both modules and Modules) it crashes.
If you see the different commits maybe it helps to understand what I was aiming to achieve.

The solution was much simpler. Now I just store the module keys with Path.GetFileName in Coverage.cs, so they can be correctly matched in CoverageResult.cs as it was done before my change.

I already tested it locally and worked for me for the example on issue #203

Hope this is clear enough!

Here's the output. Please merge!

Calculating coverage result...
  Generating report '\results\coverage.opencover.xml'

+----------------------+--------+--------+--------+
| Module               | Line   | Branch | Method |
+----------------------+--------+--------+--------+
| Rtl.ProjectName.Api         | 59.4%  | 66.7%  | 66.7%  |
+----------------------+--------+--------+--------+
| Rtl.ProjectName.Application | 100%   | 60%    | 100%   |
+----------------------+--------+--------+--------+
| Rtl.ProjectName.Data        | 24.8%  | 38.5%  | 54.5%  |
+----------------------+--------+--------+--------+

[codecov]

Codecov Report

Merging #211 into master will not change coverage.
The diff coverage is 50%.

@@           Coverage Diff           @@
##           master     #211   +/-   ##
=======================================
  Coverage   95.03%   95.03%           
=======================================
  Files          15       15           
  Lines        1590     1590           
=======================================
  Hits         1511     1511           
  Misses         79       79

Impacted Files	Coverage Δ
src/coverlet.core/CoverageResult.cs	16.21% <0%> (ø)	⬆️
src/coverlet.core/Coverage.cs	99.49% <100%> (ø)	⬆️

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[tonerdo]

Thank you!!! Gonna do a test before I make a new release

[pape77]

@tonerdo Great! Please let me know when you do as I really need this!
Feel free to test it of course. I'm pretty confident it will work :)