Major updates to linuxcncrsh (in the development version)

There has been a major re-write of the linuxcncrsh interface. 

• C-style string handling has been replaced with std::string and C-style arrays now use std::vector (that should fix the buffer overflows ).
• Many commands have been streamlined in what they allow as arguments so that similar commands use similar arguments (like -1 for 'all' and defaults)
• Output of commands has been streamlined to use identical format for same type of information
• Axis and joint indicators are now checked whether they actually are available and result in an error if they are not
• Error checking is consistently done on arguments and messages returned when something is amiss
• Heartbeat from the servo-thread (motion controller) is used to prevent RT <--> non-RT races
• GET INI - now works and you can read any INI file entry
• GET INIFILE - works and returns path of INI file
• GET PROBE now issues an MDI G38.2 because it [cw]ould not work otherwise.
• GET CLIENTS returns who is connected
• SET DISABLE lets you downgrade own connection from being enabled and also allows other clients to be downgraded
• SET JOINT_HOME (alias: SET HOME) now works in conjunction with SET JOINT_WAIT_HOMED to wait for completion
• SET JOINT_UNHOME lets you unhome any joint
• SET TIMESTAMP lets you enable date+time stamped responses
• Files read/loaded are now using a functional path (as set by the 

  -d

   command-line option). The default is 

  $HOME/nc_files

  . You can pass your own ':' separated list to the 

  -d

   option

Several GET/SET commands were removed or deprecated:

• COMM_MODE - removed - the communication is always ASCII.
• CONFIG - removed - was never implemented
• SET_WAIT - removed - was already deprecated (replaced by WAIT_MODE)
• COMM_PROT - deprecated - API versioning is overrated and is non-functional anyway
• UPDATE - deprecated - emcStatus updates are better left to be automatic
• UPDATE_STATUS - deprecated - emcStatus updates are better left to be automatic.

If users who are using linuxcncrsh and the master branch could feedback any comments or problems, that would be appreciated. 
(please comment in this thread:  forum.linuxcnc.org/41-guis/58443-linuxcncrsh-updates#343698 )