add closedir to simleshell commands that open directories
move digipot instance to CurrentControl module
make CurrentControl delete itself if not enabled
make Laser Module delete itself if not loaded
GcodeDisplay: Use iterator instead of indexing

This avoids allocations due to _M_leak since possible_command is
mutable.
Gcode: Make command const

This also kills allocations from indexing
SimpleShell: Reserve buffer before appending
Player: Pop Gcode before deleting
StreamOutput: Buffer allocated by malloc being freed with delete

Thanks to adamgr for noticing this.
StreamOutput: Kill dead code
Merge pull request #100 from bgamari/fixes

Various things encountered during search for source of heap corruption
Gcode: simplify get_value with strtod
SimpleShell: use strtol to check for valid line limit instead of int(atof(...))
Switch gcc4mbed.c license to Apache v2

I never meant for this to have a LGPL license on it.  I must have
copied that from MRI code base at some point.  I should have been
Apache v2.
Fixes issue #101

Simplified naming convention of sample config file and re-organized into
directory structure where more than one sample can live with each sample having
the correct final name of "config".

I have included a sample README.TXT file in the ConfigSamples directory that
others more knowledgable about this area may want to update.
Merge pull request #96 from wolfmanjm/upstreamedge

add closedir to simpleshell commands that open directories
Merge pull request #92 from wolfmanjm/move_digipot

move digipot to CurrentCOntrol Module
Player: Reduce block queue depth to 16

It seems we don't have enough memory to keep this many blocks around;
the heap collides with the stack on LPC1769.
Merge pull request #102 from bgamari/fixes

Player: Reduce block queue depth to 16
Gcode: Ensure queued is initialized

This was a silly and obvious oversight from
6a3328dfe514e66a98c0cf5adc7252d333567e83. Thanks to wolfmanjm for
spotting it.
Merge pull request #104 from bgamari/edge

Gcode: Ensure queued is initialized
CircBuffer: move USBSerial buffers into USB ram to conserve main ram