Update Idf.py

Fixes for bugs 0001491, 0001492, 0001493
+ allow to set deflection of a mesh with exportStl
Draft: Small fix in patterns
Draft: Downgrade now splits multi-solid compounds into individual solids
Arch: Fixed toolbar mode - fixes #1473
Arch: Added a pref option to export everything as Brep in IFC files
Arch: Axis-bbased structural systems are now a separate object - fixes #1486
Fixes to PathArray
- missing refresh() in DraftTools
- handle case where Base obj has non-trivial Placement
- copy Base obj format to PathArray object
+ Re-insert workbench box in Complete due to weird behaviour on some systems
+ fix typos or documentation
+ minor change in Vector2D
+ fixes #0001490: Implement a perimeter circle (3 point circle) similar to solidworks in sketcher (mdinger)
+ fixes: #0001475: Implement a 3 point arc similar to solidworks in sketcher (mdinger)
Find Coin3 header files on Fedora.
Merge branch 'patch-1' of https://github.com/Barleyman/FreeCAD_sf_master
Update Idf.py

Fixes from bug 1366 http://www.freecadweb.org/tracker/view.php?id=1366
+ remove plus sign