Use range-for loops for looping over strings when possible

Replace a few loops explicitly using iterators or pointers with
range-for loops.

No real changes, this is just a simplification.

src/common/fileconf.cpp

@@ -2241,9 +2241,7 @@ static wxString FilterOutEntryName(const wxString& str)
   wxString strResult;
   strResult.Alloc(str.Len());
 
-  for ( const wxChar *pc = str.c_str(); *pc != wxT('\0'); pc++ ) {
-    const wxChar c = *pc;
-
+  for ( wxUniChar c : str ) {
     // NB: note that wxCONFIG_IMMUTABLE_PREFIX and wxCONFIG_PATH_SEPARATOR
     //     should *not* be quoted
     if ( !wxIsalnum(c) && !wxStrchr(wxT("@_/-!.*%()"), c) )

src/common/textbuf.cpp

@@ -73,9 +73,8 @@ wxString wxTextBuffer::Translate(const wxString& text, wxTextFileType type)
     result.Alloc(text.Len());
 
     wxUniChar chLast = 0;
-    for ( wxString::const_iterator i = text.begin(); i != text.end(); ++i )
+    for ( wxUniChar ch : text )
     {
-        wxUniChar ch = *i;
         switch ( ch.GetValue() ) {
             case wxT('\n'):
                 // Dos/Unix line termination

src/common/txtstrm.cpp

@@ -491,9 +491,8 @@ void wxTextOutputStream::WriteString(const wxString& string)
     wxString out;
     out.reserve(len);
 
-    for ( size_t i = 0; i < len; i++ )
+    for ( wxUniChar c : string )
     {
-        const wxUniChar c = string[i];
         if ( c == wxT('\n') )
         {
             switch ( m_mode )

src/html/helpdata.cpp

@@ -887,7 +887,7 @@ void wxHtmlSearchEngine::LookFor(const wxString& keyword, bool case_sensitive, b
 }
 
 
-static inline bool WHITESPACE(wxChar c)
+static inline bool WHITESPACE(wxUniChar c)
 {
     return c == wxT(' ') || c == wxT('\n') || c == wxT('\r') || c == wxT('\t');
 }
@@ -899,9 +899,8 @@ static inline wxString CompressSpaces(const wxString & str)
     buf.reserve( str.size() );
 
     bool space_counted = false;
-    for( const wxChar * pstr = str.c_str(); *pstr; ++pstr )
+    for ( wxUniChar ch: str )
     {
-        wxChar ch = *pstr;
         if( WHITESPACE( ch ) )
         {
             if( space_counted )

src/richtext/richtextbuffer.cpp

@@ -8954,10 +8954,8 @@ bool wxRichTextBuffer::PasteFromClipboard(long position)
 #ifdef __WXMSW__
                 wxString text2;
                 text2.Alloc(text.length()+1);
-                size_t i;
-                for (i = 0; i < text.length(); i++)
+                for ( wxUniChar ch : text )
                 {
-                    wxUniChar ch = text[i];
                     if (ch != wxT('\r'))
                         text2 += ch;
                 }