Tweak to DataSet loading into R
ANOVA: Overhaul

Refactor of R code
Tweaks to UI
Fixes #28
Added unbinding to Options

Sometimes inserting a new analysis would rerun an earlier one because
of left over event listeners. Unbinding clears earlier event listeners.
Updates to documentation

Added a guide to JASPPreview
Fixed some spelling errors
Bump version number: 0.5
Updates to R style guide
Potential fix to a crash issue
Linear Regression: Hid unimplemented options
Correlation: Updates, Fixes

Implemented missing value handling.
Separated the creation of correlation tables into a separate function
for use by other code (i.e. Linear Regression would like to be able to
create a correlation table too)