irmp: rework the Python language binding for the shared library

irmp: rework the Python language binding for the shared library

Rename the Python language binding's source file and identifiers to
eliminate camel case (most of it, stick with camel case in Python class
names as is the convention). Adjust whitespace and arrange tables such
that their indentation will last during maintenance.

Re-add the license text which was missing in the original submission's
copy of another decoder. Add copyright information for this submission.

Don't "import *" from ctypes(3), use explicit references instead. Avoid
double underscores as single leading underscore is already bad enough.
Adjust the Python side to the C library's renamed API routines.

Create a result data structure layout that only has a single level of
nesting, which better represents the C library's interface. Only flags
"get unfolded" in the Python binding, to eliminate magic numbers.

Prepare to support more platforms than Linux (detected) and Windows (the
default when nothing else got detected).