Updated the list of supported container keywords.

I have added all keywords that are currently supported by the
csprocessor utility in version 0.32.0.
Updated the list of supported metadata keywords.

I have added all metadata keywords that are currently supported by the
csprocessor utility in version 0.32.0.
Made the metadata keywords case insensitive.

This is in accordance with the current implementation of the csprocessor
utility in version 0.32.0.
Added support for containers with front matter.

This is a new feature introduced in csprocessor 0.32.0.
Added syntax highlighting for TODO, FIXME, and XXX.
Added comments to the code to make it easier to read.

I have also updated the time stamp.