[supervision] add a 'flash mode' combo box

allow to select the flash mode from the paparazzi center or use board
defaults
new boards/modes have to be added to the control panel xml file (example
file reflect more or less the current state of the board makefiles)
[flash modes] change some mode names and luftboot unused by default
better test for luftboot on lisam2 and lia boards
[conf] move some flash mode vars

- lia_1.1: HAS_LUFTBOOT
[conf] separate JTAG_BMP FLASH_MODE
[conf] stm32-upload: print available FLASH_MODEs
[conf] remove FLASH_MODE from some example airframes

as it is now selectable from paparazzi center
[flash_mode] parse boards' name as regexp
[conf] fix Makefile.stm32-upload
Merge pull request #597 from paparazzi/flash_mode

[supervision] add a 'flash mode' combo box

Allow to select the flash mode from the paparazzi center or use board
defaults.
New boards/modes have to be added to the flash_modes.xml file (regex for the boards supported).

It is also possible to add custom modes in the personal control_panel.xml file.

Specifying the FLASH_MODE in the airframe file, e.g. <configure name="FLASH_MODE" value="JTAG"/> makes that the "default" for that airframe.