disambiguate isMismatchBase(), other small cleanups
Factor out SnpTable, fix crash in SNP handling
Add tests for reference position and fix refpos position off-by-one-error
Merge pull request #40 from arahuja/referenceend

Fixing reference position from offset implementation
Print a log message on startup to more easily tell runs apart
Improve BQSR performance by reducing GC pressure
Rename 'offset' to 'readOffset' and 'position' to 'referencePosition'
Merge pull request #38 from jey/bqsr

Small bugfixes and cleanups to BQSR
Make MdTag immutable
Merge pull request #45 from jey/immutable-mdtag

Make MdTag immutable
Merge remote branch 'upstream/master' into nested-variant

Conflicts:
	adam-core/src/main/scala/edu/berkeley/cs/amplab/adam/rdd/AdamRDDFunctions.scala