CSV file handling: single space now treated as NA

CSV files written by SPSS have single spaces for missing values
Fixes to t-tests
Bayesian ANOVA: temporary hiding of options

until the appropriate R code is working
Fixes to missing values in NominalText variables
Removed JASP R package imports

they cause some problems on some machines
ANOVA: Fix to text alignment

Fixes #30
ANOVA: Fixed blank table to match final
RM ANOVA: added grey lines to delineate sections
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