FIJISettingsViewer and FIJITestsViewer are widgets and can refere to
their root windows via $self->MainWindow thus there is no need to
store them additionally.

I broke it in commit 0c9547b4.

Also, add some missing strict/warning statements and fix resulting
warnings and refine some comments in the headers of files.

This makes sure that validation uses the correct values.
Otherwise the validation of checkbuttons may overwrite the values
of depending entries.

 - move necessary validation functions into Settings.pm
 - check against FIJI ports too

 - validate nets and respective drivers like everything else
 - load the netlist earlier (in the user scripts) to make it available while
   loading settings
 - add a FIJI::Netlist parameter to respective FIJI::Settings's functions
 - add a new type 'driver' for FIU elements to distinguish its string
   representation from nets'
 - add new net validation function to FIJI::Netlist
 - use this to make net and FIU validation more generic to simplify FIJISettingsViewer
 - refine and correct handling of the tool phases
 - distinguish fatal errors, missing fields and less important anomalies when
   validating settings depending on the phase etc
 - notify user about validation problems in more detailed messages and tooltips
 - refine FIJI::VHDL to not load settings all the time and receive parameters
   directly instead of via hashes
 - use a global constant ONLY_LOAD in fiji_setup instead of a local variable
 - add a 'show_warning' function to ease opening warning dialogs
 - various other usability/GUI-related improvements
 - allow the deletion of nets

as expected

Moved rebinding to function in Tk::FIJIUtils, added calls to
this function for every entry.

Addresses issue vecs/fiji#63 discovered in usability test

However, allow the user to disable these popups for the current session.

 - extract _add_driver_radiobutton_list from existing code
 - refactor it to allow it to be called repeatedly while reusing widgets
 - make some private Netlist functions public as they are used elsewhere :/
 - eliminate duplicated nets (low-hanging workaround) for a nuisance
   of _get_net_connections().
 - add FIJISearchWidget to the dialog and call _add_driver_radiobutton_list
   from its callback after filtering the driver list

Use the previous regex to validate the name only and check for a
defined non-empty string when using the names to append to indexed
names like "FIU 42".

Fix vecs/fiji#60 eventually.

 - show maximum polynomial for current LFSR width in tooltip
 - set maximum polynomial when changing LFSR width

Previously, FIJI Setup told the user only that some nets in the settings
file do not match the supplied netlist but did not state their names.
This patch adds this output to the log and GUI dialogs.

Also, fix some indentions.

* Created a method for updating all warning indicators next to the Tab names
* Corrected behavior when the FIUs indicator is on and the causing FIU is deleted

* Segfault when deselecting all nets
* When a net entry was empty (" "), the user first had to de-select this net

New feature branch: allow selection of multiple nets in FIU tab. Automatically creates FIUs for selected nets

ConfigSpecs of type METHOD should point to setter/getter methods.
If given no argument they should return the previous value.
However, some of our methods do not follow this API and hence
break things when called as getters (w/o arguments). Most of them
are not used anyway so get rid of them and fix the others.

Instead, let the caller of _select_driver_dialog handle the error messages
return by it. This fixes the output when one tries to select a driver without
a loaded netlist.

Also, fix a minor bug in the invocation of the DialogBoxUL that shows
the net selection.

Thus facilitating manual editing and understanding of the .ini files.

They are generated by DialogBoxUL automatically.

If no netlist is given, we cannot validate... but this is an expected use case
not an error.
Likewise we tried to avoid to validate if no driver was selected but failed
to do that correctly (the driver path is (probably) always defined but empty
if none was selected).