Fix error is strip spaces option to parse CSV files
Improve GDT expression lexer
Fix problem with degenerate factors in gdt.lm
Add quicksort function to sort matrix vectors
Improve gdt histograme function

The function is simpler for the user. The Freedman-Diaconis rule is
used to canculate the number of bins.
Put GDT expression eval function in a separate module
Improve gdt.plot function to determine the x variable type

Perform a lineplot or scatterplot based on x variable.
Merge branch 'gdt-new' into gdt-doc
More gdt functions documentation