GDL code borrowed from IDL: cw_lib (compound widgets) and lib (poly_fit) 

IDL versions 5 ("v5") and higher:
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Beginning with IDL 8.4, which defined an instrinsic function (LAMBDA) with
the same name as a frequently used variable in OYSTER, we need to reformat
the IDL code to follow the V5 standard, i.e. variable indices are enclosed
in square brackets, function arguments in round brackets as before.

Shell scripts idlc (csh) or idlc_sh (sh) do it all: compile V4 code, convert to
V5, compile and save to the v5 folders found in source/common and source/idl.
They also compile the IDL code library in V5 and split the containers into
individual V5 compatible source code files which are stored in source/gdl.

Command to execute idlc: ./idlc
The script executes the idl scripts idl.pro, cv5gdl.pro, and cv5.pro.

ct.pro: use this for use with tellrem.

When starting OYSTER, look for the V5 (or V4) string in the version message.

ToDo:
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2 identical versions of cv5gdl.pro, here and in source/v5.
2 identical versions of cv5.pro, here and in source/v5
