Allow `+` and `@` before a channel name as well for linkification

useful for /whois
Merge pull request #327 from glowing-bear/channelregex

Allow `+` and `@` before a channel name as well for linkification
Scroll on resize

main application of this: opening the keyboard on mobile devices
Merge pull request #328 from glowing-bear/scroll-on-resize

Scroll on resize if at the bottom of the bufferlines
Catch broken UTF-8 to enable loading of buffers with broken lines
Merge pull request #329 from glowing-bear/invalidchars

Catch broken UTF-8 to enable loading of buffers with broken lines
Replace all non-ASCII bytes with "?" in case of broken UTF-8.
Merge pull request #330 from anders/invalid-utf8

Replace all non-ASCII bytes with "?" in case of broken UTF-8.
Wrap IPv6 literals with brackets. Fixes #323.
Merge pull request #332 from anders/fix-323

Wrap IPv6 literals with brackets. Fixes #323.