Backport 'Fix for PDF texts not being selectable'

[malthe]

Co-authored-by: aziesemer [email protected]

[aziesemer]

There was a bug in this version because I was not copying save_cursor by value.
Use in cairosvg/surface.py:
import copy
...
save_cursor = copy.deepcopy((self.cursor_position, self.cursor_d_position, self.text_path_width))

See:
58ac97c

[liZe]

Hello!

I can merge this pull request when tests are fixed, but I'd like to avoid a new 1.x version: Python 2 will be dead at the end of the year, it's probably time to port old code to Python 3 instead of backporting new code to Python 2 😇.