mcy gui: small inconveniences

[nakengelhardt]

• hitting Ctrl-F again opens a second Find dialog box
• when at last match and hitting "Find Next" (or first and "Find Previous"), wraparound with small notice in bottom of find dialog would be nicer than "Text not found" popup
• sorting in "Sources" tab should be by line number rather than alphabetical
  
• show only file name in tabs, not full path (can add full path as tooltip on hover)
  
  also in properties