Add total line coverage for badge generators

[konradlipner]

Should solve #178 and #148 with regex:
/Total.*?([0-9]{1,3})(,[0-9]{1,2})?%/

[pimmerks]

Might also want to show the average of branch and method coverage like in: #104 & #123

Total Line: 100%
Total Branch: 100%
Total Method: 100%

Something like this maybe?

[konradlipner]

no problem :)

[tonerdo]

@kolipka LGTM! Please paste a copy of the terminal output with this change. Thanks!

[konradlipner]

C:\projects\coverlet\test\coverlet.core.tests\coverage.opencover.xml'

67
68 +------------------+--------+--------+--------+
69 | Module | Line | Branch | Method |
70 +------------------+--------+--------+--------+
71 | coverlet.core | 90.8% | 86.2% | 93.4% |
72 +------------------+--------+--------+--------+
73 | coverlet.tracker | 0% | 0% | 0% |
74 +------------------+--------+--------+--------+
75
76
77 Total Line 89.7%
78 Total Branch 84.6%
79 Total Method 91.7%

[Taturevich]

When this pr will be merged?