Fix MuTect2 INFO field types in the VCF header

[DonFreed]

The MuTect2 headers ECNT, TLOD and NLOD are currently strings. It is more accurate to describe these fields as integer, float and float.

[DonFreed]

This should fix bcbio/bcbio-nextgen#2033 with GATK4

[lbergelson]

@davidbenjamin This looks like one for you.

[codecov-io]

Codecov Report

Merging #3422 into master will decrease coverage by 0.427%.
The diff coverage is 100%.

@@              Coverage Diff               @@
##             master     #3422       +/-   ##
==============================================
- Coverage     80.51%   80.083%   -0.427%     
+ Complexity    17555     17482       -73     
==============================================
  Files          1175      1175               
  Lines         63499     63499               
  Branches       9896      9896               
==============================================
- Hits          51123     50852      -271     
- Misses         8425      8710      +285     
+ Partials       3951      3937       -14

Impacted Files	Coverage Δ	Complexity Δ
...e/hellbender/utils/variant/GATKVCFHeaderLines.java	99.286% <100%> (ø)	7 <0> (ø)	⬇️
...s/spark/ParallelCopyGCSDirectoryIntoHDFSSpark.java	0% <0%> (-75.51%)	0% <0%> (-17%)
...institute/hellbender/utils/gcs/GATKGCSOptions.java	0% <0%> (-66.667%)	0% <0%> (ø)
...lbender/engine/datasources/ReferenceAPISource.java	22.013% <0%> (-62.264%)	8% <0%> (-26%)
...oadinstitute/hellbender/utils/test/XorWrapper.java	13.043% <0%> (-60.87%)	2% <0%> (-6%)
...llbender/engine/spark/SparkCommandLineProgram.java	68.75% <0%> (-25%)	6% <0%> (-1%)
...oadinstitute/hellbender/utils/gcs/BucketUtils.java	53.947% <0%> (-20.395%)	29% <0%> (-8%)
...nder/tools/spark/BaseRecalibratorSparkSharded.java	10.169% <0%> (-13.559%)	1% <0%> (-1%)
...ender/engine/datasources/ReferenceMultiSource.java	70.37% <0%> (-11.111%)	10% <0%> (ø)
...titute/hellbender/utils/test/MiniClusterUtils.java	78.947% <0%> (-10.526%)	6% <0%> (-1%)
... and 8 more

[davidbenjamin]

@DonFreed I appreciate it!