+ set DBL_MAX as maximum for units
remove support for automake
+ remove some more autotools files
Sketcher Enhancement: Merge sketches

- It copies the geometry and associated constraints of a plurality of sketches into a new sketch
- The functionality is accessible from outside sketch edit mode, directly from the menu Sketch
Sketcher Enhancement: Merge sketches : Art by Jim
+ fix typo, consistent icon name
Print an error message if PySideTools are not found.