improve "Search"

[phobie]

In the search-field colons are special characters, so all keys containing colons need to be enclosed into quotation marks.
The problem is that we use ":" as THE name-space-separator in OSM and many keys contains it.
And all those special-target-strings makes generating usable search-strings even more complicated!

My suggestion to improve the usability of the search-window for end-users:

Keep the default search window and rename "Please enter a search string." to "key/value search string:"

Add CheckBoxes:

• ( ) invert search
• Type: (X) node (X) way (X) relation

Add LineEdit:

• Username: "*"

Add SpinBoxes

• OSM-Object-id: "0" (0 means any, NoButtons)
• Member count: "0" (0 means any, UpDownArrows)

Add RadioButtons:

	only	exclude	inactive
children	( )	( )	(X)
parents	( )	( )	(X)
modified	( )	( )	(X)
selected	( )	( )	(X)
incomplete	( )	( )	(X)
untagged	( )	( )	(X)