Fix issue #39 (add option to choose default svg-edit tool)

[5hir0kur0]

Description

Fixes #39.

I increased the version number by one because I added a new option (so the default value for the new option will be added to the configuration of users who have an older version installed).
If you don't want me to increase the version number I can also edit the code so it can deal with the configuration value for 'default_tool' being absent.

Currently the default tool option only applies when adding new cards but I can make it apply when editing cards too if you want (I just thought it doesn't make that much sense for that).

The config dialog now looks like this:

Checklist:

• I've read and understood the contribution guidelines
• I've tested my changes against at least one of the following Anki builds:
  • Latest standard Anki 2.1 binary build [required for Anki-compatible 2.1 add-ons]
  • Latest alternative Anki 2.1 binary build
  • Latest Anki 2.0 binary build [required for Anki 2.0-compatible add-ons]
• I've tested my changes on at least one of the following platforms:
  • Linux, version: Arch Linux
  • Windows, version: Windows 10
  • macOS, version:
• My changes potentially affect non-desktop platforms, of which I've tested:
  • AnkiMobile, version:
  • AnkiDroid, version:
  • AnkiWeb

[5hir0kur0]

I just realized that there is a better way to set the default tool so I changed my code to set the default tool vial the URL instead of clicking on it with a JS callback.

[glutanimate]

Thanks, @5hir0kur0! I could see see this being quite useful. However, I want to hold off on merging until I've worked on upgrading SVG-Edit (thus fixing a lot of the problems users are currently experiencing with the masks editor).

Will revisit this as soon as that work is done.