Ignored merge files
Added initial schematic and kicad project
Merge branch 'feature/schematic' into develop
Merge branch 'master' into develop
Added small psx description and header file
Added initial PSX bus bitbanging code
Added methods for getting button status values
Optimized c code for speed during interrupts...more still needed
Added initial int0 vector in assembly

The problem was that it appeared that it was taking too long to
execute the interrupt handler in c and so the int0 interrupt would
get called before int0 was called 8 times and reset the read mask.

The solution was to write the ISR for INT0 in assembly, trying to
optimize as best as possible to get the instructions. Also, the clock
was changed to be a 20Mhz crystal to get us some more time. According
to http://store.curiousinventor.com/guides/PS2/, for the PS1, the
bus frequency is between 100Khz and 500Khz. This gives about 8-24 ish
cycles before the next clock begins. In addition, the send queue was
abandoned in favor of using a single byte and mask for both send and
receive. For simplicity, it is assumed that when the mask is nonzero,
it is sending/receiving. Once the mask is entirely shifted off, the
byte has been sent/received, and so the ISR can ignore anything past
that point.
Added psx main and set received flag

A test of making the light light up with received == 0x01 passed, so
it does appear to be receiving properly

Started ack logic
Changed to use internal SPI for reading PSX bus

Receive appears to pass the flash check when receiving 0x80

It was discovered that 0x01 makes for 0x80, so it would appear the
byte order is reversed
Found the reverse data order flag and set it
Switched oscillator back to 8Mhz internal R/C
Added ack functionality which passes blink test

The test here was to say ack on 0x01. If pd0 lit, it worked. Then,
don't ack on 0x01. If pd0 didn't light, it worked.
Changed command parsing structure and confirmed communication to pc

Confirmation was by setting the two button bytes to 0x00 and seeing
that all buttons were registered as off. Next, the button bytes were
set to 0xff and it was seen that all the buttons were registered as
pressed.
Added button update method to main loop and sent button data

Button update method was optimized to work decently fast. Before, we
were missing keypresses. The newer method removes volatile
restrictions and stuff. Hopefully it is also easier to read.
Fixed polarity of button presses
Merge branch 'feature/psx-spi-slave' into develop
Merge branch 'develop'