Only collect regular files, not special devices
Handle file under-read

In sysfs all files are reported as 4K in size but provide a variable
size based on real content, in those cases we read a lot of zeroes
and wasted some space and made things less conventient to work with.

Now we adjust the total file size if the first read was below the first
buffer size.
Add GLOB collection

For now the internal collection is not done completely in parallel.
Add possible collectors in README.md
Add a sample list of collections
Ignore empty lines and comments