Add an LFUN for continuous spell checking

This fixes the first part of #8589.

src/FuncCode.h

@@ -456,6 +456,7 @@ enum FuncCode
 	LFUN_VC_RENAME,                 // gb 20130205
 	LFUN_VC_COPY,                   // gb 20130205
 	// 355
+	LFUN_SPELLING_CONTINUOUSLY,     // vfr, 20130324
 	LFUN_LASTACTION                 // end of the table
 };
 

src/LyXAction.cpp

@@ -1045,6 +1045,16 @@ void LyXAction::init()
  * \endvar
  */
 		{ LFUN_SPELLING_REMOVE, "spelling-remove", ReadOnly, Edit },
+
+/*!
+ * \var lyx::FuncCode lyx::LFUN_SPELLING_CONTINUOUSLY
+ * \li Action: Toggle continuous spell checking.
+ * \li Syntax: spelling-continuously
+ * \li Origin: vfr, 24 March 2013
+ * \endvar
+ */
+		{ LFUN_SPELLING_CONTINUOUSLY, "spelling-continuously", ReadOnly, Edit },
+
 /*!
  * \var lyx::FuncCode lyx::LFUN_THESAURUS_ENTRY
  * \li Action: Look up thesaurus entries with respect to the word under the cursor.

src/frontends/qt4/GuiView.cpp

@@ -1855,6 +1855,10 @@ bool GuiView::getStatus(FuncRequest const & cmd, FuncStatus & flag)
 		enable = documentBufferView() && documentBufferView()->cursor().inTexted();
 		break;
 
+	case LFUN_SPELLING_CONTINUOUSLY:
+		flag.setOnOff(lyxrc.spellcheck_continuously);
+		break;
+
 	default:
 		return false;
 	}
@@ -3758,6 +3762,12 @@ void GuiView::dispatch(FuncRequest const & cmd, DispatchResult & dr)
 			one.startscript(Systemcall::DontWait, command);
 			break;
 		}
+
+		case LFUN_SPELLING_CONTINUOUSLY:
+			lyxrc.spellcheck_continuously = !lyxrc.spellcheck_continuously;
+			dr.screenUpdate(Update::Force | Update::FitCursor);
+			break;
+
 		default:
 			// The LFUN must be for one of BufferView, Buffer or Cursor;
 			// let's try that: