Trimmed trailing white space.
Bug fix for option -lower-

Option -lower- may now be specified. Previously this resulted in an
error message.

There is now also an informative error message if options -lower- and
-upper- are both specified.
Bug fix for option -trim-

Previously, option -trim- would always result in an error message.
Fixed error message.

There is now an informative error message if a variable specified to
option -t1vars()-, -t2vars()-, or -t3vars()- is numeric in one dataset
and string in the other.
Changed the help file extension to .sthlp.
Added .gitignore file.
Trimmed leading white space from the help file.
Added markers to the help file.
Modernized the top of the help file.
Modified the acknowledgements section.
Modified the stored results section.
Modified the "also see" section.
Modified the author section.
Modified the top of the syntax section.
Restyled SMCL directives.

Replaced {syntab :} with {syntab:} and {synopt :} with {synopt:}.
Added links to -help filename- to the syntax section.
Updated the syntax options.
Updated the description.
Updated the options section of the help file.
Updated the examples section of the help file.