Add new Cols-based methods.
Remove unused ColumnSelection code.
Delete unused code.
Merge branch 'master' into topic/cols

Conflicts:
	modules/pframe/src/main/scala/pellucid/pframe/Frame.scala
Clean up Rec constructors.
WIP: blah
Merge remote-tracking branch 'upstream/master' into topic/cols

Conflicts:
	modules/pframe/src/main/scala/pellucid/pframe/ColumnSelector.scala
Generalize Cols code to be re-used in Rows.
Use AxisSelction for Cols.
Move AxisSelection type member to type parameter.
Add some helper methods to Cols/Rows.
Merge remote-tracking branch 'upstream/master' into topic/cols

Conflicts:
	framian-json-base/src/main/scala/framian/json/JsonExtractor.scala
	framian/src/main/scala/framian/ColumnSelector.scala
	framian/src/main/scala/framian/csv/CsvRowExtractor.scala
	modules/pframe/src/main/scala/pellucid/pframe/Series.scala
Get asArrayOf, asListOf, etc working correctly.
add foreach and variants to Series

- general foreach
- foreach for dense series, with unboxed access to values
- foreach, just the keys
- foreach, just the cells
- foreach for values of dense series, with unboxed access to values
rename Series .values .denseValues to .cells .values

- aiming for more consistent naming with other methods
- rewrite to more low-level implementations
mark Series .size .keyAt .valueAt with @inline
renaming for Series .cellAt and valueAt
Merge branch 'master' into topic/series-foreach

Fix tests due to change of
 - Series.values -> Series.cells
 - Series.denseValues -> Series.values

Conflicts:
	framian/src/main/scala/framian/Series.scala
Add sortBy method.
Merge branch 'master' into topic/series-foreach

* master:
  Improve coverage for Series.zipMap
  Add tests for Series.closestKeyTo
  Remove unneeded s
  Add test for Series.++
  attempt at stabilizing the Travis-CI builds

Conflicts:
	framian/src/test/scala/framian/SeriesSpec.scala