Use case suggested by @romkatv uses zle-line-init to restore buffer
after running a widget to cd up one level (GitHub #431).

As far as I can tell, the ignoring of zle-line-* was added in commit
9788c2e to support some deprecation warnings that were removed some time
ago.

The pattern was then widened in commit 0c940e7 to zle-* to fix problems
encountered when wrapping zle-isearch-update.

This commit removes the hard coded ignore of all zle-* widgets and adds
zle-* to the default list of widgets to be ignored. Users who want the
plugin to wrap zle-line-init or zle-line-finish can override the
default.