vfs:zip issues

[sander]

When the vfs:zip package is not installed, the emoticons panel in the preferences does not work and gives strange errors.

[Mats (matsben)]

I haven't been able to figure out the logic of the package needs in all situations, and it seems to fail at some point:

    # We need the 'vfs::zip' package and if not using starkit we also need
    # the 'Memchan' package which is not automatically checked for.
    # 'rechan' is the tclkits built in version of 'Memchan'.
    if {[catch {package require vfs::zip}]} {
 set priv(havezip) 0
    } elseif {![catch {package require rechan}]} {
 set priv(havezip) 1
    } elseif {![catch {package require Memchan}]} {
 set priv(havezip) 1
    } else {
 set priv(havezip) 0
    }