Defining Option Tree

Defining Option Tree (e.g. Linking to Option Trees)
- There are multiple ways of linking in or specifying option trees so that NeXtMidas can find them. In all cases the path must match Java package naming conventions (e.g. primitives use the package name nxm.<opt>.prim and must be in a nxm/<opt>/prim/ directory).
  The "Recommended" Way (this is how you will do it in training)
  Explicitly specifying the option tree's location using option (works all platforms).
```
nm> option myopt "/home/midas/options/myopt123/nxm/myopt/"

--- for the following directory structure / layout ---
/home/midas/options/myopt123
                      +- nxm
                      |   +- myopt
                      |   |  +- cfg
                      |   |  +- mcr
                      |   |  +- prim
                      |   |  +- test
                      |   |  ...
```
  Option trees using this setup can easily be versioned (e.g. myopt version 1.2.3).
  
  Creating your option trees in a separate directory will allow you to easily upgrade and/or switch NeXtMidas versions without having to modify anything under the NeXtMidas installation. (Good practice.)
  
  Using "Links" (UNIX only - NOT recommended)
  Specify the option tree's location using a symbolic link under $NMROOT/nxm/. For example:
```
nM> option/link=nxm myopt /home/student/myopt123
```
  In this example the option tree would be named MYOPT and the directory structure would look like:
```
$NMROOT
  +- nxm
      +- myopt --> /home/student/myopt123
      +- sys <existing>
      +- ucl <existing>

/home/student/myopt123
                +- cfg
                +- prim
                +- mcr
```
  Option trees setup using this method will be automatically picked up by NeXtMidas and do not need to be specified using the OPTION command (after creation).
  
  Unfortunately this only works in Unix (Windows users will need to use another approach).
  
  This also requires you to have write access to the $NMROOT/nxm directory to make modifications to it.
  
  Other Methods (see OPTION explain file)
  
  Putting the entire option tree under $NMROOT/nxm/. (Rarely used because people want to keep their option trees separate from the NeXtMidas baseline, this is a good thing. NOT RECOMMENDED.)
  
  Putting a "back-link" in the option tree directory. (This is strongly discouraged because it causes serious problems for many IDEs (Integrated Development Environments). NOT RECOMMENDED.)