Implement function checkconfig that checks the consistency of cfgs, similar to checkdata for data structure.

Implement function checkconfig that checks consistency of cfgs:

1. For the user: input cfgs should be adjusted when necessary and possible, and feedback (warning/error) should be given when required options are missing or when forbidden or deprecated options are used. This should replace the current 'backward compatibility' code.
2. Internal use: checkconfig should control the relevant cfg options that are being passed on to other functions.
3. Output: only relevant cfg fields should be contained in the output (data.cfg), e.g. it should not contain unused default settings.

Overview of relevant functions (where checkconfig should be implemented):

• preprocessing ——step1=done——
• private/preproc (uses cfg.preproc)
• artifact functions ——step1=done——
• timelockanalysis ——step1=done——
• freqanalysis ——step1=done——
• sourceanalysis ——step1=done——
• private/prepare_dipole_grid (uses cfg.grid)
• statistics functions!!
• perhaps also other private functions that take a cfg as input

Overview of existing relevant functions:

• createsubcfg
• checkconfig
• check_cfg_unused
• check_cfg_required

Add the check (objective 1) to the existing functions.

Required: check whether required options are present, give error when missing

• e.g.: sourceanalysis: method; xxxstatistics: method
• …(perhaps in general search for cfg.method using grep and check whether this is a more common required feature)

Renamed: change old options/values into new ones + give warning

• this should replace most of the backward compatibility code regarding renamed options and values

Deprecated: give warning when deprecated options are used

• search for that using grep

Forbidden: give error when forbidden option is used

• e.g. cfg.trl when calling preprocessing on data that has already been read

Incorporate existing functions in checkconfig:

• createsubcfg - done -
• dataset2files - done -

Control the output cfg:

• report on used/unused fields (trackconfig)
• remove unused fields from output cfg (trackconfig)
• remove large fields from output cfg (checksize)

trackconfig:

• controlled via ft_defaults or overruled by cfg.trackconfig: 'report', 'cleanup', or 'off'
• start of each FT function: cfg=checkconfig(cfg) » if user requests report or cleanup, configtracking is turned on
• end of each FT function: cfg=checkconfig(cfg, 'trackconfig', 'off')

checksize:

• controlled via ft_defaults or overruled by cfg.checksize: inf or number in bytes
• end of each FT function: cfg=checkconfig(cfg, 'checksize', 'yes')