A Military Engineer can build roads, airstrips, and forts.  Normally only 2.  I have just changed its build limit to 20 to allow it to build long roads which go where you want rather than where the Trader puts them.  it is intended to be only used for roads, but obviously it could be used to build lots of airstrips and forts.  That is why i have categorised it as a cheat.
It is my first Mod, so please shoot it down (or improve upon it) freely.
It is activated by default.

Upon request from CountVertigo I have created a 7 build version.