Add basic conditional formatting writer support.

examples/xlsx/conditionalformatting/main.cpp

@@ -0,0 +1,56 @@
+#include <QtCore>
+#include "xlsxdocument.h"
+#include "xlsxconditionalformatting.h"
+
+using namespace QXlsx;
+
+int main()
+{
+    //![0]
+    Document xlsx;
+    Format hFmt;
+    hFmt.setFontBold(true);
+    xlsx.write("B1", "(-inf,40)", hFmt);
+    xlsx.write("D1", "[30,70]", hFmt);
+
+    for (int row=3; row<22; ++row) {
+        for (int col=2; col<22; ++col)
+            xlsx.write(row, col, qrand() % 100);
+    }
+    //![0]
+
+    //![1]
+    ConditionalFormatting cf1;
+    Format fmt1;
+    fmt1.setFontColor(Qt::green);
+    fmt1.setBorderStyle(Format::BorderDashed);
+    cf1.addHighlightCellsRule(ConditionalFormatting::Highlight_LessThan, "40", fmt1);
+    cf1.addRange("B3:B21");
+    xlsx.addConditionalFormatting(cf1);
+    //![1]
+
+    //![cf2]
+    ConditionalFormatting cf2;
+    Format fmt2;
+    fmt2.setBorderStyle(Format::BorderDotted);
+    fmt2.setBorderColor(Qt::blue);
+    cf2.addHighlightCellsRule(ConditionalFormatting::Highlight_Between, "30", "70", fmt2);
+    cf2.addRange("D3:D21");
+    xlsx.addConditionalFormatting(cf2);
+    //![cf2]
+
+    //![cf3]
+    ConditionalFormatting cf3;
+    Format fmt3;
+    fmt3.setFontStrikeOut(true);
+    cf3.addHighlightCellsRule(ConditionalFormatting::Highlight_BeginsWith, "2", fmt3);
+    cf3.addRange("F3:F21");
+    xlsx.addConditionalFormatting(cf3);
+    //![cf3]
+
+    //![2]
+    xlsx.save();
+    //![2]
+
+    return 0;
+}