Add Micro QR code support

[Shane32]

Prerequisites (to reduce diff):

• Split alphanumeric encoding from QRCodeGenerator, split encoding tables #590

Status:

• All generated micro QR codes are scannable
• Most QR codes match the output of the segno python library
• Need to add tests and validate combinations of lengths, character types, etc

Side notes:

• ASCII small generator has x/y swapped and prints inverted compared to regular ASCII generator
• The segno python library does not apply padding properly so micro QR codes consisting mostly of padding don't match

[Shane32]

M2 codes will generate correctly now

[Shane32]

Still a little more work to do, but it appears to be generating readable codes for all micro QR code sizes now.

[Shane32]

This implementation is complete. I might add some more tests but everything is working.

[gfoidl]

I'm looking forward to review the PR, but after #590 got merged so I can focus on the new stuff.

@Shane32 👍🏻 for your work