Allows selected environments to be included/excluded
Description
The package defines an environment that only typesets specified
environments within its scope. So, for example, if you want
nothing but the figure and table environments in your document,
you can enclose the whole document with an xcomment environment
that excludes everything but. This is a lot easier than
excluding the chunks of text between the environments you want,
or creating an entire document containing only those
environments. The package was previously part of the seminar
bundle for typesetting presentations.
