Check of nesting depths may fail

[matze-dd]

In the section on implementation issues of README.md, checks for nesting depths of braces and environments have been mentioned. They do fail, if braces or environment frames are inserted via expansion
of a declared macro.

One could reject recursive declaration of macros, but this would reduce
flexibility.

[matze-dd]

Currently, the checks are performed after removal of % comments.
A fix would be to re-check, whenever a brace is inserted by a macro expansion, which in turn is easily detected.

[matze-dd]

Fixed with release 1.5.2

[matze-dd]

The version from release 1.5.2 does not check inclusion of [] brackets and \begin or \end of environments.
Furthermore, we also should perform the tests at replacements for "normal" and equation environments with fixed text.

[matze-dd]

Closed in master after release 1.5.2