PD profile cycling and better Display init

This release is especially thanks to tuna-f1sh, see this commit for more information..

The Iron will now choose one of the following PD profiles, preferring the highest voltage.

• 20V
• 15V
• 12V
• 9V
• 5V

The Display should initiate more reliable.

Current Display [partly broken?]

This release adds current readout and displays the measured current.

It seems that on some OtterIrons this release adds some noise to the measured temperature (+-30°C), if that happens please use v0.3.

Serial communication [BROKEN]

Please use v0.5 https://github.com/Jan--Henrik/Otter-Iron/releases/tag/v0.5

This release adds serial communication to the Otter-Iron via USB CDC :3

v0.41 update: added watchdog due to critical overheating bug when USB fails

non-volatile memory update

With this release your TS100 will remember it's set-point, won't overshoot anymore, shows a better DFU-screen and get a nice power-showing-bar! Temperature control is now much more advanced... Much less crappy at least. :3

yay, bootloader!

This release adds a dfu-bootloader (to enter press both buttons while plugging in, display will show "dfu") and a cascade controller (Two-step controller + PID, faster heating and less overshoot). Firmware is still shitty af ^^

dfu-utils usage:

dfu-util -a 0 -s 0x08000000:leave -D firmware.bin

It works... somehow

This release adds basic functionality, the firmware however is far from ready. If you flash this release you will be able to set a temperature and solder. Setpoint, current temperature, heating status and input voltage are shown on the display.