allow python3 and add quiet mode

This allows the code to be the same for python2 and python3 when we are printing messages and improves the CLI, making a help message automatically and documenting the different user options.

Closes #1 (closed)

Tests

I tested this manually with four different Python versions (v2.7.18, v3.10.6, v3.11.2). For each Python version, I ran four different commands.

1. python[3] readMilleBinary.py uncorrupted.bin : default printing of first 10 records
2. python[3] readMilleBinary.py --num-records -1 uncorrupted.bin : print headers-only but look through entire file
3. python[3] readMilleBinary.py --num-records -1 --quiet uncorrupted.bin: look through entire file, only printing summary at the end
4. python[3] readMilleBinary.py --num-records -1 --quiet corrupted.bin: look through entire file, making sure it catches the corruption

uncorrupted.bin is a copy of an example file I've used with HPS and is available online (click to download, ~66M). corrupted.bin is created by only copying the first X bytes from uncorrupted.bin using dd: dd bs=1 count=66359000 if=fee_recon_20um120nA_197_mille.bin of=corrupted_mille.bin.

The output of all four different commands is the same across the different python versions.

Happy to do more testing if you think there are other things to check!