Ok, I got this working on my laptop with Linux Mint 18 and Arduino IDE 1.8.0.
1. First I installed the Arduino SAM Boards (Arduino Due) and SAMD boards (Arduino Zero, M0, etc) from the Boards Manager in the IDE.
2. Downloaded the Arduino_STM32 hardware files from https://github.com/rogerclarkmelbourne/Arduino_STM32
3. I extracted the files into Arduino/hardware/Arduino_STM32
4. Ran the udev rules installation script in Arduino/hardware/Arduino_STM32/tools/linux64/install.sh
5. Restarted the Arduino IDE.
6. The tricky part, select the Maple(Rev3) board and the port /dev/ttyACM0
7. I don't know if this step was neccesary but I installed dfu-utils from repositories:
sudo apt-get install dfu-utils
I don't remember if I did anything else besides this but I already loaded a blinking program.
To load a program:
1. Press the Reset button
2. Quickly press the Boot button while the led is flashing rapidly, and hold for a couple of seconds until the led flashes slower steadily, then release. It should stay flashing slowly.
3. Download the program.