Mark above as read

Hi,

first of all, thank you for the great app :)

### Use Case
After a day, the list of unread articles is sometimes quite large for me.
When reading them successively, I don't make it through the entire list of articles (I don't read them all, as not all article is interesting).
For example, if I have 100 articles unread, I might be able to go through the first 50 before I have to do smthg. else.
Nonetheless, I want to "save" that I "scanned" the first 50 articles and mark them read.
Marking each article individually is quite time consuming and tiring.

### Suggestion
Like other readers (e.g., Inoreader), having a context menu entry to mark all articles in the list above as read.