Added SAMD21 symbols

[DerekGn]

http://ww1.microchip.com/downloads/en/DeviceDoc/SAMD21-Family-DataSheet-DS40001882D.pdf

ATSAMD21E15A-AUT

ALIAS
ATSAMD21E16A-AUT ATSAMD21E17A-AUT ATSAMD21E18A-AUT ATSAMD21E15B-AUT ATSAMD21E16B-AUT ATSAMD21E17D-AUT

ATSAMD21E15A-MUT

ALIAS

ATSAMD21E16A-MUT ATSAMD21E17A-MUT ATSAMD21E18A-MUT ATSAMD21E15B-MUT ATSAMD21E16B-MUT ATSAMD21E17D-MUT

ATSAMD21E15L-AUT

ALIAS

ATSAMD21E16L-AUT ATSAMD21E17L-AUT

ATSAMD21E15L-MUT

ALIAS

ATSAMD21E16L-MUT ATSAMD21E17L-MUT

ATSAMD21G15A-AUT

ALIAS
ATSAMD21G16A-AUT ATSAMD21G17A-AUT ATSAMD21G18A-AUT ATSAMD21G15B-AUT ATSAMD21G16B-AUT ATSAMD21G17D-AUT

ATSAMD21G15A-MUT

ALIAS

ATSAMD21G16A-MUT ATSAMD21G17A-MUT ATSAMD21G18A-MUT ATSAMD21G15B-MUT ATSAMD21G16B-MUT ATSAMD21G17D-MUT

ATSAMD21G16L-MUT

ALIAS

ATSAMD21G17L-MUT

ATSAMD21J15A-AUT

ALIAS

ATSAMD21J16A-AUT ATSAMD21J17A-AUT ATSAMD21J18A-AUT ATSAMD21J15B-AUT ATSAMD21J16B-AUT ATSAMD21J17D-AUT

ATSAMD21J15A-MUT

ALIAS

ATSAMD21J16A-MUT ATSAMD21J17A-MUT ATSAMD21J18A-MUT ATSAMD21J15B-MUT ATSAMD21J16B-MUT ATSAMD21J17D-MUT

All contributions to the kicad library must follow the KiCad library convention

Thanks for creating a pull request to contribute to the KiCad libraries! To speed up integration of your PR, please check the following items:

• Provide a URL to a datasheet for the symbol(s) you are contributing
• An example screenshot image is very helpful
• Ensure that the associated footprints match the official footprint library
  • A new fitting footprint must be submitted if the library does not yet contain one.
• If there are matching footprint PRs, provide link(s) as appropriate
• Check the output of the Travis automated check scripts - fix any errors as required
• Give a reason behind any intentional library convention rule violation.

[cpresser]

See #2336 (comment)

[cpresser]

SAMD21 family has been added in #2336