Add result count to search and rewrite scroll past end feature (#946)

* Restore colours to dark theme search-replace icon
* Implement a working search result counter
* Disable scroll past end feature and clean up search/replace and update test
* Re-implement scroll past end feature as a static distance
* Stop the search box from resizing on every search

tests/test_gui/test_gui_guimain.py

@@ -199,7 +199,6 @@ def testGuiMain_Editing(qtbot, monkeypatch, nwGUI, fncProj, refDir, outDir):
     # Change some settings
     nwGUI.mainConf.hideHScroll = True
     nwGUI.mainConf.hideVScroll = True
-    nwGUI.mainConf.scrollPastEnd = True
     nwGUI.mainConf.autoScrollPos = 80
     nwGUI.mainConf.autoScroll = True