TPAC: Preserve loc, query, qtype, and sort params

TPAC: Preserve loc, query, qtype, and sort params

In some cases, mkurl() is not enough to preserve our desired CGI params
- such as when redirects are triggered from within a Perl module, or
forms are submitted. Accordingly, the following changes address these
cases where the chosen location / query / query type was being dropped:

* Switching between account preferences
* Creating / deleting / sharing / editing bookbags
* Moving items from temporary list to bookbags
* Adding notes to items in a bookbag
* Placing holds

The primary mechanism for forms is the "preserve_params.tt2" block that
can accept a "params" list of the CGI params that you want to preserve,
but which defaults to location/query/qtype/sort. Similarly, we add the
same preservation steps to the OpenILS::WWW::EGCatLoader::Account module
for most actions.

Signed-off-by: Dan Scott <dan@coffeecode.net>