Remove trailing delimiters from csv_from_result

When using the csv_from_result function, the returned string includes an
extra delimiter at the end of every line, usually a comma unless another
delimiter is specified.  A simple addition of a couple of lines to
remove the extra delimiter from the column names and the data rows is
included. (Lines 241 and 251)
[ci skip] Add application/x-zip for OpenOffice docs in application/config/mimes.php
added spaces after the parameter separators
Text helper: convert_accented_characters() optimization

Thanks to static variables, array_keys() and array_values() are now executed once only.
Merge pull request #2294 from vlakoff/develop-2

Text helper: convert_accented_characters() optimization
Merge pull request #2290 from jonesmdj/develop

Remove trailing delimiters from csv_from_result
Optimize changes from PR #2290
Merge pull request #2287 from vlakoff/develop

Fix this use case: load->vars->('foobar', '')