Add AbstractTextDumper to implement stream holding and indendation

src/ObjWriting/Dumping/AbstractTextDumper.cpp

@@ -0,0 +1,28 @@
+#include "AbstractTextDumper.h"
+
+#include <cassert>
+
+AbstractTextDumper::AbstractTextDumper(std::ostream& stream)
+    : m_stream(stream),
+    m_indent(0u)
+{
+
+}
+
+void AbstractTextDumper::Indent() const
+{
+    for (auto i = 0u; i < m_indent; i++)
+        m_stream << "  ";
+}
+
+void AbstractTextDumper::IncIndent()
+{
+    ++m_indent;
+}
+
+void AbstractTextDumper::DecIndent()
+{
+    assert(m_indent > 0);
+    if (m_indent > 0)
+        m_indent--;
+}