TechManager Tech Tree Support

Add a sub-tree, or "branch" of the stock tree that contains Impossible
Innovations parts. 2 parts, the aluminum strut and the dead weight are
located in the stock tree. Powered by TechManager.

Removed some typos, played with more price balancing.

Discovered that not every part cfg needs to be named 'part.cfg'! So I
renamed every single one to make it easier for me to edit.

New models for struts, radial battery, and 2 tanks!

Radial battery is now scalable.
More Changes

Made the iridium strut just a tad darker...

Decided to only use 1 new tank texture, rather than the 2 that were
given to me.

Refined node positions on new x8 tank model.

Made all nodes size 1. That means no more massive nodes in your way when
trying to place a part that was once large!

Something was screwy with the x1 tank's node positions. All fixed now.
Added KSP-AVC Support

Adds a .version file in JSON format. This makes Impossible Innovations
compatible with cybutek's mod, KSP-AVC, a version-checking plugin.

You do not have to install KSP-AVC, but the option is now available to
you if you want to use it.