Fix some typos in docs and apidocs

While "commonest" is still correct English, it's rather old-fashioned
and "most common" predominates Qt's wording style.

Change-Id: I20d72c098ee40b2a89f91e42f7208fe5b87286a2
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@qt.io>

src/corelib/doc/src/eventsandfilters.qdoc

@@ -80,7 +80,7 @@
 
     \section1 Event Types
 
-    Most events types have special classes, notably QResizeEvent,
+    Most event types have special classes, notably QResizeEvent,
     QPaintEvent, QMouseEvent, QKeyEvent, and QCloseEvent. Each class
     subclasses QEvent and adds event-specific functions. For example,
     QResizeEvent adds \l{QResizeEvent::}{size()} and

src/corelib/io/qurl.cpp

@@ -149,7 +149,7 @@
     dealing with URLs and strings:
 
     \list
-    \li When creating an QString to contain a URL from a QByteArray or a
+    \li When creating a QString to contain a URL from a QByteArray or a
        char*, always use QString::fromUtf8().
     \endlist
 */

src/corelib/kernel/qcoreapplication.cpp

@@ -1031,7 +1031,7 @@ bool QCoreApplication::notifyInternal2(QObject *receiver, QEvent *event)
   approaches are listed below:
   \list 1
   \li Reimplementing \l {QWidget::}{paintEvent()}, \l {QWidget::}{mousePressEvent()} and so
-  on. This is the commonest, easiest, and least powerful way.
+  on. This is the most common, easiest, and least powerful way.
 
   \li Reimplementing this function. This is very powerful, providing
   complete control; but only one subclass can be active at a time.

src/corelib/tools/qregularexpression.cpp

@@ -542,7 +542,7 @@ QT_BEGIN_NAMESPACE
     \inmodule QtCore
     \reentrant
 
-    \brief The QRegularExpressionMatch class provides the results of a matching
+    \brief The QRegularExpressionMatch class provides the results of matching
     a QRegularExpression against a string.
 
     \since 5.0