Releases for Multiple file loader front end

This 3/22/2010 release incorporates the following changes
--Added data structure (structJTG_MFL) to hold the list of selected file names and path to disk folder holding those files. The goal is to make easier to pass this data onto a file loading function.

--Modified popFuncList Popup Menu on the panel. This Popup Menu can be used to select a function to process the list of selected files. All functions in memory ending in "_MFL" will be included in the list. File processing functions must take as a single input a structure of the type structJTG_MFL. A numeric constant (kHideFunctionList) at the top of the procedure file controls whether the Popup Menu is enabled or not. If the popup menu is not hidden, the selected function will be called once the list of selected files is compiled.

--Because of the change to the behavior of popFuncList, the KnownFuncLists string variable has been removed from the function that creates the panel (MultiFileLoad).

--Fixed start up behavior of the panel so that the list box is filled with files from the default disk folder in ksDefaultDataPath. If that path doesn't exist, Igor pops up a dialog to find it.

--Provided a means to limit the types of files displayed in the list box. This is done using the fileTypeOrExtStr parameter of the IndexedFile function. Currently, the default behavior is to list files with the extension ".spc". However, all files in the folder could be listed, using the "????" form of fileTypeOrExtStr. For now this is easily (but not terribly transparently) done using a string constant (ksFileTypeOrExtension) at the head of the procedure file.

--Although this version has been created with Igor 6.12A, it should still be compatible with version 5.00 and greater.

Removed file loading specific code and generalized output so that a string list of selected files is compiled and stored in the panel specific data folder.
This should prove easier for the Igor programmer to incorporate into their own code.

See main description. This is the first version.