Additional overloads for get()

[tclune]

Currently YAML_Node has getters for scalars:

• integer (INT32 and INT64)
• real (REAL32 and REAL64)
• logical
• string
  There are also getters for 1D allocatable arrays of the above except string.

The Fortran use case for 2D arrays is common enough that it is probably worth adding an accessor for this.

Possibly add an interface to get non allocatable arrays. Would need a different method name though.

Possibly also add support to get() gFTL containers:

• StringVector
• IntegerVector (32 & 64)
• RealVector (32 & 64)
• LogicalVector