Add new Allegro current sensor footprints
These are the footprints needed for the library update at https://github.com/KiCad/kicad-library/pull/1817.
Datasheet links:
- PSOF: http://www.allegromicro.com/~/media/Files/Datasheets/ACS780-Datasheet.ashx
- QFN: http://www.allegromicro.com/~/media/Files/Datasheets/ACS711-Datasheet.ashx
- QSOP: http://www.allegromicro.com/~/media/Files/Datasheets/ACS726-Datasheet.ashx
- SIP-4: http://www.allegromicro.com/~/media/Files/Datasheets/A1363-Datasheet.ashx
- SIP-3: http://www.allegromicro.com/~/media/Files/Datasheets/A1369-Datasheet.ashx