disable verbose logging for XServer, fixes #4333

The current options for the XServer produce a huge amount of log messages. The
server produces around 70-80 messages per minute. The most messages look like
this:

display-manager-start[1846]: GetModeLine - scrn: 0 clock: 75200
display-manager-start[1846]: GetModeLine - hdsp: 1366 hbeg: 1414 hend: 1478 httl: 1582
display-manager-start[1846]: vdsp: 768 vbeg: 772 vend: 779 vttl: 792 flags: 9

Since theses messages aren't very useful, I propose to remove the `-logverbose`
and `-verbose` options from the XServer arguments.
Add a script to add git branches for each channel.
Add other source of channels, and distinguish between local and remote channels.
update-channel-branches.sh: Add verbosity to improve the user experience, and update NixOS documentation.
add League of Moveable Type fonts

Conflicts:
	pkgs/top-level/all-packages.nix
add TeX Gyre fonts
add LaTeX Project Public License v1.3c for Gyre

use lib.maintainers
nixos-option: Print the outPath of derivation for option values.
nixos-option: Print derivation outPath within attribute sets and list, when the strict mode is used.
nixos-option: Improve error messages to avoid reporting internal location and traces.
include version number in name

league provides no version number, so use date
mp3gain: Add package

This adds mp3gain which is a normalizer for mp3 audio files.
nixos-option: Handle 'attrsOf submodule' options.
nixos-option: Produce nicer error messages in case of typos.
nixos-option: Support -I option.
Merge pull request #5412 from devhell/mp3gain

mp3gain: Add package
fix maintainer information
s/maintainer/maintainers
libtoxcore: bump, build DHT bootstrap daemon
Fix license attribute of many bsd-like licensed packages
nixos: tox-bootstrapd service