Revert "Set port variable instead of placeholder"

This reverts commit 6b4d2fddbb5859c2ef0ebdcbf133b21006daeffc.

...because it didn't work. I just got an empty box and the variable wasn't set
Set placeholder text to "Port" instead so it is clear what is needed here
Don't trim unread lines

Also fix read marker after trimming
Remove duplicate source of truth with buffers.
Merge pull request #345 from kramerc/remove-duplicate-sot-with-buffers

Remove duplicate source of truth with buffers.
Merge pull request #344 from glowing-bear/fixlinetrimming

Don't trim unread lines
Allow a minus sign before a #channel link
Merge pull request #343 from glowing-bear/defaultport

Fix default port
Merge pull request #346 from glowing-bear/channelregexonceagain

Allow a minus sign before a #channel link
Fix the name in the Firefox App
Fix the Chrome manifest while we're at it