Bed Level Visualizer, Repetier 1.0x and G32 command output

Repetier 1.0.x firmware reached end of development and I decided to hack it a little bit and add Bed Level Visualizer "friendly" output to G32 command. Before this change the only way to get bed map into Bed Level Visualizer was to run G32 followed by G33 command, which means distortion correction had to be enabled even if it is not needed.
I added P parameter to G32. G32 P1 generates output with actual data, G32 P2 generates 3x3 test output that helps to properly configure Flip and Rotate in Bed Level Visualizer settings. I call this a hack because it only works with BED_LEVELING_METHOD=1 (grid measurements) that I use. Leveling methods 0 and 2 are not supported.

Tested and works with Octoprint 1.3.12/BedLevelVisualizer 0.1.12 and Octoprint 1.4.2/BedLevelVisualizer 0.1.15

If anyone is interested, I can share the code.