Search in memory view

Adds a search to each memory view control. There are two modes, depending on which side is highlighted.
-if ascii is highlighted, then it'll just search for the string that was input
-if the hex data is highlighted, then it'll parse the input string as a sequence of bytes. Like "FF FF FF" or "AABBCC". Spaces are optional

Ctrl+S or Ctrl+F to start, Ctrl+C to continue, Escape to cancel an active search.