add new lines to the start and end of each structured text section

[aeu485]

Addresses #10. Works upon ST declaration and implementations, with the --lines argument for specifying additional \n.
Two modifications occur from the use ElementTree.Write:

• xml version line changes from double to single quotes and encoding is capitalized
  <?xml version="1.0" encoding="utf-8"?>
  becomes
  <?xml version='1.0' encoding='UTF-8'?>
• Folder tags Id attributes lose a space at their end
  <Folder Name="internal" Id="{ad4fec99-008a-4786-b366-d1f41be17bb4}" />
  becomes
  <Folder Name="internal" Id="{ad4fec99-008a-4786-b366-d1f41be17bb4}"/>

[ZLLentz]

This is well implemented and a good addition, thank you!
I'm stalling out a bit on review due to some busy season/staffing shortages, it will take me a bit longer to verify the versioneer update (I know it's stock and standard, but it's also a big diff and I can't accept it without reviewing it thoroughly)

[aeu485]

No problem. I removed the versioneer updates as you didn't update in your most recent PR either.

[ZLLentz]

Things I like:

• Works as advertised! (if you modify slightly to make the hook entry and the python file names match as per my other comment)
• The resulting files are still readable by TwinCAT and compile normally

Things I'm not crazy about (still going to merge regardless):

• Since lxml modifies the xml header, this actually applies to every POU on every commit as it continually fights TwinCAT. This isn't a unique problem to this PR though, the xml formatter has the same thing. Maybe some day I'll come back through and figure out how to (if it is possible?) to make lxml behave.

[ZLLentz]

This needs to be named twincat_st_newline.py for setup.py to automatically pick it up and provide it to pre-commit as a console script. (The entry names are generically mapped to module names).

[ZLLentz]

Thank you for updating these too!

[ZLLentz]

merging and then I'm going to make a mini follow-up PR to rename the file so it will run from the pre-commit binary

thank you for your contribution and your patience!