XML generated by conditions is not optimized for Simgear

[sanhozay]

Given a condition such as:

a && b && c

The generated output follows the structure of the parse tree, which ends up like:

<and>
  <and>
    <property>a</property>
    <property>b</property>
  </and>
  <property>c</property>
</and>

It should probably output the more readable:

<and>
  <property>a</property>
  <property>b</property>
  <property>c</property>
</and>

The nested form is valid and works perfectly well, but the optimized version is what an aircraft developer would write.

[sanhozay]

Fixed in 1.1.1.