update version strings to 0.4.2-dev
fix incorrect propagation of dtype in Series normalize and other methods
Replace hyphen with underscore
Merge remote-tracking branch 'upstream/0.4.x' into 0.4.x
move apply method up to Data from Images and Series; __finalize__ method docstring changes
specify float64 output from Series correlate
enforce float-valued Series data, remove casting in Series operations
update test expectations for new Series data types
cast series binary data to float on loading; prevent series cast to int via astype
remove cast to float on writing series binary data, remove check against explicit casting series to non-float
fix SeriesLoader data type handling; add data type assertions to tests
Merge pull request #46 from industrial-sloth/0.4.x

fix incorrect propagation of dtype in Series normalize and other methods
merge Series data type changes from 0.4.x