Fetch more lines on request
Fix scrolling issue and reduce the number of scrolling events on startup

Don't trigger scrolling on each line when batch loading lines
Dynamically load lines for each buffer on startup

Add setting for number of lines to fetch initally.

TODO: styling
Fix issue with incorrect read marker on startup
Make the code a little prettier
Remove setting and calculate number of lines from display properties
Merge pull request #133 from lorenzhs/fetchmorelines

Dynamically fetch lines