add Export button to search results

[Jamiras]

Implements the "save" portion of #775. I'm still not convinced that it's beneficial (or even viable) to be able to load search results.

Adds an "Export" button to the search results panel:

Clicking the button prompts the user for a filename, which will be populated with a csv of the current search results:

Address,Value,PreviousValue,InitialValue
0x000000,0xc0,0x8b,0x8b
0x000001,0x28,0xd6,0xd6
0x000002,0x7e,0x8d,0x8d
0x000004,0x0c,0xd3,0xd3
0x000007,0x00,0xff,0xff
0x000008,0x00,0xa7,0xa7
0x000009,0x00,0x83,0x83
...

Which can then be imported into a spreadsheet program for additional analysis.