Merge pull request #298 from wolfmanjm/upstreamedge

Panel displays Printing when getting gcodes from pronterface or such
make console defaults in src/makefile slightly less machine specific
Swap ringbuffer around the right way
get_tail_ref was also mis-named, should be get_head_ref
Consolidate planner's block queue scan
Remove unused parameters to Block::reverse pass and Block::forward_pass
Merge branch 'fix/Ringbuffer' into edge
Merge branch 'fix/Queue_scan_consolidation' into edge

I keep being told that if I want something tested, merge it into edge
Revert "Merge branch 'fix/Queue_scan_consolidation' into edge"

This reverts commit b4f9b9b5b4186df5a681dc63cd4174c543cd41d7, reversing
changes made to d97f94e3d8782e77793011430bb38784640b1f6f.

needs more work
found an off-by-one, see if this works
found another off by one, starting to wonder how original code ever worked
works! hooray! add some final cleanups and clarifications
Revert "Revert "Merge branch 'fix/Queue_scan_consolidation' into edge""

This reverts commit e918c030e3ced39ce7d6f8d7a66d1ce8bb78e7d9.
Merge branch 'fix/Queue_scan_consolidation' into edge
Use static kernel singleton pointer instead of per-class instance pointer
replace all uses of module::kernel pointer with kernel::instance singleton pointer
Replace all doubles with floats including some constants
replace strtod with strtof
replace sqrt, hypot, sin, cos with float variants (ie sqrtf, hypotf, sinf, cosf)
missed an atan() in Robot, changed to atanf