Drop unneeded compound double quote macros.
Update option abbreviations.
-using- is not optional.
-error_overlap- handles tokens with embedded spaces and quotes.
Observation number of first problematic row saved in `first'.
Rework check of word count of `namevar'.
Remove unnecessary -local- parsing quotes.
-egen rownonmiss()-: use -str- option abbreviation.
Drop unused local.

s(headers) is no longer defined.
White space changes
Use Stata variable names rather than XLSForm column headers.
Add missingness check of list label column.
Update comments in -adorn_quotes()-.
Slight tweaks to -strip_quotes()-
Calculate -strlen(s)- just once.
Improve treatment of parameter mode.

mode is handled correctly if args() == 3. Also adding a check of mode.
++ is safe in one-line blocks.

In contrast, it isn't safe in Stata one-liners.
Remove \n from -error()-.
Update debug output.
White space changes