keyword: wrap functions only once at loading keyword extension
Before this patch, some functions are wrapped in reposetup(), but this
causes redundant nested wrapping, if two ore more repositories enable
keyword extension (e.g. hgweb serves multiple repositories).
Now, there is no need to define these wrapper functions in
reposetup(), because previous patches made them not directly refer to
kwtemplater instanciated in reposetup().
This patch factors these wrapper functions out from reposetup(), and
uses them to wrap functions only at once at loading keyword extension.