Added first, last, showall, getindex(gd, I::AbstractArray{Bool}) for GroupedDataFrame
Added setindex!(g::SubDataFrame,v,c)
fixes deprecated parse_float parse_int
Merge pull request #239 from milktrader/master

fix deprecated parse_int parse_float
Add "each" capability to `rep`.
Change insert_single_column! to allow AbstractVectors.
Merge pull request #233 from kmsquire/gdf_updates

Added first, last, showall, getindex(gd, I::AbstractArray{Bool}) for Gro...
Modify Formula, Terms, ModelFrame and ModelMatrix

to more closely follow R conventions.
Check for an integer NA in the R index vector for a factor.

In addition to using an index of 0 in a factor to indicate missing data, some
index vectors end up with an integer NA value.
Avoid use of an explicit uint16 for converting the refs in a PooledDataArray

The practice now is to use POOLED_DATA_VEC_REF_CONVERTER
New version of ModelMatrix

The current approach is to use

mf = ModelFrame(f::Formula, d::AbstractDataFrame)

to create the model frame, followed by

mm = ModelMatrix(mf)

to create the model matrix.  The response is retrieved with

y = model_response(mf)

Still work to be done.
Changes that should have gone in the previous commit but somehow didn't.
Change import of names from the Sort module
Import functions and types from Base.Sort for which methods will be added.
Better show for IndexedVectors.
Use complete_cases for na_omit operation (thanks to Tom Short).
Merge remote-tracking branch 'origin/master'
Consistency in converters for PooledDataArray refs.
Fix #245, rbind stack overflow.
Small fix to enable zero-row DataFrames