Bugfix in .spt file export

The original value.strip("'") call strips ALL single quotes at the start and end, not just the first and last ones inserted by repr.

This create an error when exporting a string finishing with a single quote

for example a python trigger finishing with:
return 'foo'

becomes:
return \'foo\''

after repr and:
return \'foo\

after strip

the resulting exported .spt file will have a multiline string finishing with:
return \'foo\"""

escaping one of the three double quotes and giving an error when reread by tactic.