Show information on current state of learning#5

The statistics give an overview on the progress for specified time periods, however it would be great to also have a good unterstanding on the “current state2.

It would be great to have an overview on:

• amount of words in total
• amount of words in each level
• how often has each word been repeated?
• what have I learned today? (also in relation to the day before and daily average)

It would be great to also have this for filters / tags too. So if I have a tag called adjectives, I can click it and see clearly how many words are unlearned and how many are in each of the different stages of learning. This could be in a little histogram that changes for each tag, and shows the totals for all words when no tag is selected