IDE: Optimization of modification events processing in text editors.

Too many modifications types where registered, and then too many events were fired.
Also, in case of uninterrupted sequence of events, updates to the model is deferred to the end of that sequence (wx.Callafter).

                  <xsd:element name="Linux">
                    <xsd:complexType>
                      %(toolchain_gcc)s
                    </xsd:complexType>
                  </xsd:element>