feat: automatically skip large file systems

[halpomeranz]

Adding a new configuration variable, exclude_mount_size. If non-zero, exclude any file systems (except the root file system) that are using more than than the specified amount of disk space. May use usual size units-- for example, "4T" for terabytes. Default is zero, which disables this feature. Per Issue #415

[tclahr]

Don't you think it would be good to use bytes as the size unit as min_file_size and max_file_size support bytes only?
Also, in avml the avml_max_memory variable is also defined in bytes.

I can do the proper changes if you agree.

[halpomeranz]

To turn this around, wouldn't it be cool if all of these parameters accepted the units that _convert_size_to_kb() does?

We could take the logic from _convert_size_to_kb() and make a _convert_size_to_bytes() function. Then refactor _convert_size_to_kb() to call the new _convert_size_to_bytes(). The parameters that currently expect bytes could just be filtered through _convert_size_to_bytes() directly.

Yes, I was put on this earth to make life difficult. :-)

[tclahr]

Ok, I can rename _convert_size_to_kb to _convert_size_to_bytes and use it to convert max_file_size and min_file_size.

We could make it a helper function (same as command_exists), so it could be called by command collector, used in conditions etc. We could call it size_to_bytes().

[tclahr]

I did some changes and merged into develop.