Introduce a global variable cfg_list which holds all cfg ids (not eids)

Introduce a global variable cfg_list which holds all cfg ids (not eids)
for currently open projects.

Move previously global variable currentFile to per-cfg namespaces, given
that each project should typically correspond to a different file.

Rename proc newFile to newProc, and slightly reorganize it so that
newProc does all necessary steps for setting up a project environment
inside the GUI.

Introduce proc setWmTitle which should be used exclusively for updating
window title.

Deprecate procs fileOpenStartup and fileNewDialogBox.

It is no longer necessary to set up the default config namespace in
imunes.tcl and initgui.tcl, given that proc loadCfg and proc newFile
now initialize all the necessary state.

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