interp/remap: improve support for remapping builtin codes

The G_REMAPPABLE and M_REMAPPABLE macros were getting a bit baroque.
Replace these macros by a bitset lookups, add init code for same.
interp/remap: make G28/G28.1/G30/G30.1 remappable
interp/remap: add G28/G28.1/G30/G30.1 example to remap/getting-started
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
Merge pull request #182 from luminize/vel-control-extruding

config : add pressure adjustment functionality on top of other changes
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
.gitignore: linuxcnc-xenomai.files is now ignored