Reads a file, decompresses it and writes it to standard output.
readgzfile() can be used to read a file which is not in gzip format; in this case readgzfile() will directly read from the file without decompression.
filenameThe file name. This file will be opened from the filesystem and its contents written to standard output.
use_include_pathYou can set this optional parameter to 1, if you want to search for the file in the include_path too.