More activity icons (etc) for Isotrident ( / Isophex)
On the forum, GriffonSpade has added various extra-specific activity icons, and made other tweaks.
Tiles: added road, rail, maglev, outpost, fortress, airstrip, airbase, irrigation, farmland, mine, oil_mine, oil_rig, buoy. (This version is based on Trident) Removed defunct nuke sprite(s) (Tileset uses a separate, single image) and pointed references to mushroom cloud sprite (Should these be completely removed for 2.6 or wait until 3.0?). Cleaned dirty transparent pixels.