Despite myLayouts currently being more popular in examples, make
them all myLayout as in man/xmonad.hs to avoid mixing them in the
same module as was done a few places, leading to confusion for some users.
The latter is pretty useless, as there's no way to find out what
layouts are available, but it can at least allow you to select between
any layouts that you happen to be using already (in one workspace or
another). The former is handy any time you'd rather have a short name
for a layout (either for selecting, or for viewing in a status bar).
