Search should be able to parse key=value

[xeen]

The current syntax only allows key:value. This has three disadvantages:

• The wiki uses key=value
• the "special searches" might conflict with normal tags (i.e. "type:")
• the difference between "tag search" and "special search" isn't obvious

At least key=value should be supported as well.

[stoecker]

This has been considered and dropped. Wontfix.