We often use the pattern «map global normal ": foo"». The space
after the colon is unnecessary since execution of the mapping won't
add to history anyway, since 217dd6a1d (Disable history when executing
maps, 2015-11-10).
With the parent commit, the space is no longer necessary for user
mappings, so there is no reason to continue the cargo-cult.
Remove the space from mappings to set a good example.
This allows to jump from a mail buffer that contains an inline diff
to the source files (most accurate when the patch has been applied
locally).
This makes the diff module a mandatory dependency; we could relax that.
