Modified Search Features

Enabled searches to act on custom post type for assignmwnt/things. If
you want wider search (examples),  remove the hidden field from
header.php and use a plugin line
https://wordpress.org/plugins/search-everything/
Revert "Modified Search Features"

This reverts commit 325826c0d7b37d0f45476dc713cfdfa13eb0aee4.
Search For Things

Modified search form in header.php to force search of custom post types
assignments (searches for things/assignments), and formatted output
(search.php) to reflect this. If you want wider search, remove hidden
field in header.php and use Search Everything plugin
https://wordpress.org/plugins/search-everything/