This separates the menu-syntax portions of fluxbox.txt out into its own man
page, and includes a rather large rewrite of much of fluxbox.txt, as well as
small improvements in other pages.
This now shares the CLIENT PATTERNS section in common with fluxbox-keys(5), so I
split this out into a client-patterns.txt which is included by both
fluxbox-apps.txt and fluxbox-keys.txt.