rtapi_shmem: retrieve the size of an attached segment.

This was likely an oversight and is needed for introspection, boundary checks,
and a useful Python API to RTAPI shared memory segments.

Fixes #178 .
halmodule: enable attach to existing rtapi shm segment
Merge pull request #180 from luminize/vel-control-extruding

config -> update and relocating of config files for velocity extruding
Merge pull request #179 from mhaberler/rtapi-shmem-size-param

RTAPI: retrieve the size when attaching a shared memory segment

After a discussion with Michael, this API change looks mostly internal.  While it could be used externally in a comp, it looks unlikely, and even more so at this early stage of Machinekit's existence.  Therefore, we're not going to worry much about the 'Evolution of Public Contracts' section of C4 [1].

Merging patch.

[1] http://rfc.zeromq.org/spec:22#toc8
config : break up very long lines
Merge pull request #182 from luminize/vel-control-extruding

config : add pressure adjustment functionality on top of other changes
script : fix of bug in postprocess script w.r.t. recharging

When the post processing script finds a retract anchor, it replaces
that with the M commands for retracting. Meaning setting the time
of the retract (time = 0 means 0 seconds retract disconnecting of
the extrudion with the motion). in some cases the anchor for that
in the slic3r generated code is off, resulting in the time being set
after the retract (so no retract) and a precharge then gives too much
script : add fix for timing of setting of retract time in layer
script : remove test comment
Merge pull request #184 from luminize/vel-control-extruding

script : fixes for setting of retracting time when disconnecting extruder from motion
Fix RTAI kernel detection for newer RTAIs

The ShabbyX repo, and probably RTAI 4.0, don't have the rt_daemonize
symbol in the i-pipe patch that older versions did.

This patch recognizes newer RTAI kernels by keying off of
rtai_irq_handler as well.
fixed missing libxaw7-dev build dependency.

forced tcl/tk version to 8.5 (this is valid everywhere except for Lucid)
Merge pull request #186 from zultron/mk-pull

Fix RTAI kernel detection for newer RTAIs
Merge pull request #187 from kinsamanka/fix_#185

Partial fix for #185
configs : Update BeBoPr-Bridge/++ to use official device-tree overlay

Signed-off-by: Charles Steinkuehler <charles@steinkuehler.net>
configs : Update BeBoPr-Bridge default homing settings
Allows "home-all" to work

Signed-off-by: Charles Steinkuehler <charles@steinkuehler.net>
Merge pull request #188 from cdsteinkuehler/config-bebopr

Update BeBoPr Configs
- all emcweb parameters can now be specified using the ini file
- updated sample config to allow running of the default nc files without complaining about axes limits
- allow running in non-RIP environment
added packaging for emcweb
- removed remaining hard-links
- simplified emcweb parameters