Added structure to the script and an example

[ghost]

Because the script was in an appalling state, I rewrote it and made the following changes:

• code is in line with PEP 8 standards
• BuildDEB class for use with other scripts as an API
• main class and method/function
• added an example package
• edited README
• used SYS.ARGV (ArgParse is so unneccesary in this case!)
• classic "if name == "main" construct. (Makes code more readable) Could you please edit the README aaccordingly?

[fornwall]

Thanks a lot! I cleaned up the script now and split it into functions - improvements should now be be made on the updated file.

I've kept the --prefix /usr variant for now to avoid breaking existing scripts, and to avoid having to specifiy build termux for every invocation.