TmuxCheatSheet: Increase max-width to 400px

The columns collapse before it even reaches 380px.
Merge pull request #788 from duckduckgo/jag/tmux-mobile

TmuxCheatSheet: Increase max-width to 400px
CalendarConversion.pm now uses YAML instead of YAML::XS. Fixes #790.
Merge pull request #792 from MoriTanosuke/790-fix-yaml

CalendarConversion.pm now uses YAML instead of YAML::XS.