Split tags by space, not comma

[p3lim]

It's way more intuitive in my opinion, fixing uncertainties like in #9.

If not merged as-is, please provide it as an option.

[p3lim]

For those who wants to test this, I created a signed XPI file from this PR (and my other 3) available on my fork: https://github.com/p3lim/shiori-web-ext/releases/tag/0.8.4

[hasso]

I use a lot of tags containing spaces. I think that I'm not the only one.

[fmartingr]

Thanks for your contribution @p3lim, but I'm in the same boat as @hasso: my tags contains spaces and I'm used to commas for list separation (which is the same being used in the shiori frontend). Maybe some kind of autocompletion for tags will be more useable? (that way pressing would append the tag and the comma automatically, or with a special tag input of some sort).

Since the extension will still remain in beta for some time until I sort everything in the org I'm leaving this behaviour as is, in the meanwhile we can open a feature request to discuss how to move forward with this one.