org-agenda-list should respect org-agenda-max-entries

[Ag Ibragimov]

While going through the source code, I've noticed that org-agenda-list scans 
all the files in org-agenda-files and processes all Org items those files 
contain.

However, it seems when org-agenda-max-entries or org-agenda-max-todos are not 
nil, it still processes every entry, and only after building the agenda it 
reduces the number of items in the list. It's okay, but if you have lots of 
files and tons of entries, it seems to be waste of time and resources.

Just wanted to bring someone's attention to that. Thank you!