An @command must either start at the beginning of the line and be
followed by whitespace or EOL, or it must be followed by a brace.
Colorizing just any "@text" string colored too much.
Also, allow an @} and another @command{} within a pair of braces,
colorize only the valid @-commands with uppercase in their names,
unbold enclosed command arguments, colorize the directory entries
for the manual, and properly colorize also the comments that use
the full @comment command.
Reference:
https://www.gnu.org/software/texinfo/manual/texinfo/html_node/Command-List.html
Testing was done with:
info texinfo @-C "Command List" --output=list
sed -i -e "s/^'//" -e "s/'$//" list
nano list -Ytexinfo
Since file-5.10 (end of 2011), libmagic identifies a C file in most
cases as "C source" instead of as "C program". Nano's magic strings
for some other files didn't match any more what file-5.32 currently
produces, either. So, they have been adjusted, new ones added, and
old ones deleted.
This fixes https://savannah.gnu.org/bugs/?52445.
Benno Schulenberg