tsview --figsize-img & relaxed subset tmpl reading

[yunjunz]

Description of proposed changes

• tsview: add --figsize-img option to be able to customize the map figure size. Make this arg optional so that other existing functionalities won't be affected.

• subset.read_subset_template2box:

  • support mix separator/delimiter of : and , so that values from isce-proc also work
  • replace try/except with if judgment

Reminders

• [x] Pass Pre-commit check (green)
• [x] Pass Codacy code review (green)
• [x] Pass Circle CI test (green)
• [x] Make sure that your code follows our style. Use the other functions/files as a basis.
• [x] If modifying functionality, describe changes to function behavior and arguments in a comment below the function declaration.