Tidied NMOSFET stuff in Discretesemi library.
- Removed separate device for SOIC-8 NMOSFET
- Removed separate BSS138 NMOSFET device
- Added pinout-correct BS170 and 2N7000 parts
- Added all SparkFun stocked NMOSFET devices to library.
Added QFN-28-5MM-1:1 package to PowerIC.lbr

and linked it to the A4983 Device to be used on the new Quad Stepper
Motor Driver board. This package has a 1:1 imported .bmp image of the
particular IC and the pads have been updated to better fit the chip on
the board.
Added 2X5_NOSILK package to connectors.
Added part number to 7408SE part in DIGITAL_IC.
Adding FT231X device to DigitalIC.lbr

Added 9V battery pth holder to Electromechanical.lbr.
Added "kit" versions of RG and RGB encoders (only have exposed copper on
one side of annular ring). Added to Electromechanical.lbr.
Added new Top up Switch package, TACTILE_SWITCH_SMD-3.
Update README

Fixed the link to the old pre-6.0 library.
Mostly part number info
Aesthetics- Add four layer board warning
AnalogIC- add part number to LMV358
Connector- add part number to RA 1x3 .1" header
 - add 2x3 simple package, with and without silk
Digital- add part number to PCA9306, add part and value to symbol
 - Add part information to TXB0104
PowerIC- add dedicated MIC5205 part
Resistors- add 200k
Sensors- add part info to QRE1113
 - add part info to MMA8452Q