Custom Food constructed from individual meals

[beekama]

Up to now, food can only be created as a whole from scratch. This means that for the whole food, the nutritional values have to be determined and commuted independently.
Another way to create a meal is to create foodgroups, but you can't save them.

We need:

• option within create-custom-food that lets us select to create a foodgroup (and name/save it)
• perhaps also the option to save a foodgroup afterwards (from journal)

[FAUSheppy]

Implemented as:

• Button in Journal, saves group as loggedAt = -1
• is Listed in custom foods
• when clicked in custom foods, redirects to the group overview of the journal with an extra boolean isTemplate to differentiate it from editing "real" logged groups

Todo:

• implement delete meachnism in CustomFoodsOverview

Maybe todo:

• add a good group name section to the database
• add a isTemplate to the database for good meassure

Commits:
c29a8d3

[FAUSheppy]

3e4c5f3

Bug: Can save Food groups as templates from Journal when in Edit mode (aka, create->go back to journal->go into group again).