Remove build output and editor files from the current version

Visual Studio build output (.obj, .pdb, .tlog, .sdf, .suo, ipch) of the 2012 IK visualiser and Unity's .vs, Logs and UserSettings of the 2018 simulation. They stay in the history. The built 'Hexapod app.exe' (Debug) is kept. Also drops the per-folder .gitattributes of the Processing sketch (the repo root now defines how files are stored) and the 2016 README of the old Hexapod repo (its only content was a GitLab link).

2012-simulation/processing-3d/.gitattributes

@@ -1,2 +0,0 @@
-* text=auto
-*.pde text