Version 1 release: updates to L2 trigger

First version with all functionality included.

Major changes in L2 trigger:

• Add triggered pixel output (a number from 0 - 2303)
• Make the trigger threshold configurable (N_BG is the number of times above background level)
• Make the lower limit of the threshold configurable (LOW_THRESH is the lowest allowed trigger threshold)

Inputs/outputs were implemented in the same way as previous IO (n_pixels in_bus and trig_data) to the trigger block.

The configurable parameters:

• N_BG is a uint8_t with an s_axilite port bundled into the CTRL_BUS
• LOW_THRESH is a uint32_t with an s_axilite port bundled into the CTRL_BUS

The output triggered pixel:

• trig_pixel is a volatile int * with an ap_ovld port

Scurve adder IP is unchanged.