Also cleaned up some constants in top-level file.

The CSR now has individual bits controlling pulse generation, LED
sequencing and setting the RTM blocking pulse LED lines for testing them
and the RTM detection lines.

The doc files for the PTS have also been moved to the main doc/ folder,
and work on pts_hdlguide has restarted.

PDF files for the schematic and BOM for the RTM Tester Board are
also added.

old_rep_test/ folder is not pulse_gen/

The old and incorrect PCB projects have also been deleted in this
commit.

The design files for the tester board are added as part of this commit.
Additional changes to make the TTL pulse repetition test are also part
of the commit. These changes include adding a pulse_gen on CH10 and
additional changes to pulse repeaters, such as enable inputs, etc.

Apart from this, a watchdog counter has been integrated into the
i2c_slave VHDL module; it resets the slave FSM after one second
if the master does not cycle the SCL line.

I2C slave working, with ELMA protocol on top. Submitting last changes + doc for I2C slave. Also updated order-record doc

Basic functionality with immunity to no input channel while in INV-TTL mode and documentation update.

Basic pulse repetition operational. Folder structure pretty much the same as before, but pulse repetition files exist in <pulse_generator> folder. <release> folder holds release version for the firmware.

Added old repeater boards' test. New project folder hierarchy started, as exemplified in old_rep_test/ folder.