Detect and report potential errors in formatting blocks

[robertjank]

Sometimes formatting blocks get messed up. Examples are:

• 'text':class="block3control"} Opening brace { missing.
• 'text'{: class = ""} Empty value string between double quotes ".
• (text): target = "_ blank"} Opening { missing.
• 'text'{;class="block3looks"} Semicolon ; used instead of colon:.
• 'text':{class="block3looks"} Opening brace { and colon : swapped.
• 'text'{:clsss="block3looks"} Keyword class misspelled as clsss.

NTTT may not be able to fix these kinds of errors (because that may require knowledge about the context), but should help the user to locate these errors, such that the user can fix these errors manually.

NTTT should be extended such that it can detect these kind of errors and report them to the user of NTTT.
False positives (NTTT reports a potential error, which turns out not to be an error) should be as small as possible. (This requirement should be quantified, because now it is not verifiable).