Improve group filters

[michaelschattgen]

This PR moves the group filters from the EntryListView to the MainActivity as shown in the screenshots below.

Tapping the "All" placeholder group will uncheck all the groups and set the filter to null.
Changing the filter will make a 'Save' button appear at the end of row to set the selected filter as default.

I'm not entirely sure if the "Save" button at the end of the row is intuitive since it will be quite hidden for our users with less screen estate or with a lot of groups, but I think it does the job for now and we can always look into this in the future.

Fixes #1406
Fixes #914

Closes #628
Closes #1219

[alexbakker]

Very, very nice! A couple of remarks:

• This reintroduces Screen rotation cancels group selection #762. We probably need to move the fix from Remember group selection after screen rotate #1382 to the main activity.
• This essentially reverts ce9a15b. Do we still want the ability to filter on "No group"?

[alexbakker]

I think we're missing an updateDividerDecoration() call somewhere. When adding a couple of entries, the offset between entries is missing:

[tiniwings]

Pill group click should be an automatic selection of that category like radio box selection.

Click on Work, it should automatically show only Work group.

Click on Games, it should now show only Games group.. Like a filter.

Clicking on All will clear all filter and shows everything.

By this way its easy to switch between the groups with one click.

Edit: I see the same from your previous screen share example. Is new implementation different from it?

#914 (comment)

[michaelschattgen]

@tiniwings thanks for chiming in. The way I implemented this is just like in the screen share you mentioned. After your comment and bazzik's comment over at #914 (comment) we decided to change the pills to a 1-tap in our next update since our users probably prefer it that way. Maybe in the future we will allow multi-select by long pressing but that's not a high priority right now.

Will have updates on this soon.