Swap QString::replace using trivial QRegExp expressions with simple

QString variants

Rationale:
1. It's *much* faster
2. I managed to get a valgrind report from the intermittently crashing
PyQgsRulebasedRenderer test, which indicated the crash related to
the use of QRegExp in qgsexpressionlexer.ll. Let's see if this has
any impact on that crash....

Author: nyalldawson

src/core/qgsexpressionlexer.ll

@@ -33,7 +33,6 @@
 #include "qgsexpression.h"
 struct expression_parser_context;
 #include "qgsexpressionparser.hpp"
-#include <QRegExp>
 #include <QLocale>
 
 // if not defined, searches for isatty()
@@ -59,7 +58,7 @@ static QString stripText(QString text)
   text = text.mid( 1, text.length() - 2 );
 
   // make single "single quotes" from double "single quotes"
-  text.replace( QRegExp( "''" ), "'" );
+  text.replace( "''", "'" );
 
   // strip \n \' etc.
   int index = 0;
@@ -86,7 +85,7 @@ static QString stripColumnRef(QString text)
   text = text.mid( 1, text.length() - 2 );
 
   // make single "double quotes" from double "double quotes"
-  text.replace( QRegExp( "\"\"" ), "\"" );
+  text.replace( "\"\"", "\"" );
   return text;
 }
 

src/core/qgsvectorlayer.cpp

@@ -3600,7 +3600,7 @@ QString QgsVectorLayer::metadata()
     //
     myMetadata += "<p class=\"glossy\">" + tr( "Layer Spatial Reference System" ) + "</p>\n";
     myMetadata += "<p>";
-    myMetadata += crs().toProj4().replace( QRegExp( "\"" ), " \"" );
+    myMetadata += crs().toProj4().replace( '"', " \"" );
     myMetadata += "</p>\n";
 
     //
@@ -3611,7 +3611,7 @@ QString QgsVectorLayer::metadata()
     //myMetadata += "<tr><td bgcolor=\"gray\">";
     myMetadata += "<p class=\"glossy\">" + tr( "Project (Output) Spatial Reference System" ) + "</p>\n";
     myMetadata += "<p>";
-    myMetadata += coordinateTransform->destCRS().toProj4().replace( QRegExp( "\"" ), " \"" );
+    myMetadata += coordinateTransform->destCRS().toProj4().replace( '"', " \"" );
     myMetadata += "</p>\n";
 #endif
   }

src/plugins/georeferencer/qgsgeorefplugingui.cpp

@@ -1241,7 +1241,7 @@ bool QgsGeorefPluginGui::loadGCPs( /*bool verbose*/ )
   {
     line = points.readLine();
     QStringList ls;
-    if ( line.contains( QRegExp( "," ) ) ) // in previous format "\t" is delimiter of points in new - ","
+    if ( line.contains( ',' ) ) // in previous format "\t" is delimiter of points in new - ","
     {
       // points from new georeferencer
       ls = line.split( ',' );