added Alps EC11 and EC12 rotary encoder footprints

Created by: jkriege2

• made to match generic symbols from device.lib (see also https://github.com/KiCad/kicad-symbols/pull/206)
• variants with and without switch
• for now 20mm shaft lengtrh variants (given height for future 3D models, variants with other shaft lengths can come in future)
• variants with circular holes for mounting-pins
• mounting pins are assigned pin0 to allow connecting them to a shield explicitly with symbols from https://github.com/KiCad/kicad-symbols/pull/206
• datasheets:
  • http://www.alps.com/prod/info/E/HTML/Encoder/Incremental/EC11/EC11E15204A3.html
  • http://www.alps.com/prod/info/E/HTML/Encoder/Incremental/EC12E/EC12E1240405.html
  • http://cdn-reichelt.de/documents/datenblatt/F100/402097STEC12E08.PDF
• cross marks axis center on F.Fab and F.Silks

check against 3D models from ALPS: EC11

These images show that the ALPS models fit the footprints:

check against 3D models from ALPS: EC12

These images show that the ALPS models fit the footprints:

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