+ Fixed merge of cells to retain value in upper left cell+ Replaced std::map::at() with iterators and find. Removed some superfluous calls to std::map::find()

+ Visual Studio fixes
+ Fixed return values
+ Removed unused variables

src/Mod/Spreadsheet/App/SheetPyImp.cpp

@@ -416,7 +416,6 @@ PyObject* SheetPy::getStyle(PyObject *args)
 
 PyObject* SheetPy::setDisplayUnit(PyObject *args)
 {
-    int row, col;
     const char * cell;
     const char * value;
 
@@ -842,7 +841,6 @@ PyObject* SheetPy::setRowHeight(PyObject *args)
 PyObject* SheetPy::getRowHeight(PyObject *args)
 {
     const char * rowStr;
-    int row, col;
 
     if (!PyArg_ParseTuple(args, "s:getRowHeight", &rowStr))
         return 0;