Initial commit of isNoData and isData macros.

Still need to figure out how to make those functions import nicely
with just `geotrellis._`. Aims to fix #624
isNoData and isData macros in geotrellis package

Converted all comparisons to their macro equivalent

z == NODATA                -->  isNoData(z)
z != NODATAT               -->  isData(z)
java.lang.Double.isNaN(z)  -->  isNoData(z)
!java.lang.Double.isNaN(z) -->  isData(z)
Added unit test for very strange compiler break.
Fixed issue with BitArrayRasterData override of map.

This map was not lazy by default like the other maps.
In addition to this, the old implementation would blow up the compiler.
I don't know why.
Merge pull request #642 from lossyrob/BitArrayRDBug

Fixed issue with BitArrayRasterData override of map.
Merged in upstream BitArrayRasterData fix
Merge pull request #639 from lossyrob/isNoData-macro

isNoData and isData macros