All DOSes: Foundation required for disk/volume verification

[tomas-nestorovic]

Each of implemented DOSes currently lacks the functionality of verifying disk integrity, usually under disabled menu item DOS → Verification.

This issue aims to prepare the necessary general foundation so that disk integrity of each DOS can be easily implemented without the burden of paying attention at recurrent details (and logical action flows) that may arise when implementing the verification for individual DOSes. This issue should thus give the following common assets, leveraged by all DOSes:

• A dialog with options of what integrity checks are possible and where the user could interactively choose which ones to perform, just a little bit detailed than the following one.
• A progress window in which particular action currently running is displayed in bold in a list of actions to perform (and eventually with additional note under it), in similar fashion as the following Windows 95 dialog. Naturally, modern assets must be injected into the window appearance (e.g. more advanced layout, or thread priority selection).
• A disk surface checker thread, common for verification in all DOSes. The range of sectors checked for readability (and eventually writeability) should be constrained to only those part of the current volume (e.g. MS-DOS disks may contain more volumes).

[tomas-nestorovic]

With no modifications or fixes for more than a year, this issue can be safely closed.