32-bit libsxbp

Amend sxbp to be type-compatible with v0.26.0 of libsxbp
The latter is now 32-bit compatible

Update for renamed dependency

The dependency libsaxbospiral has been renamed to libsxbp.
This release amends sxbp appropriately to handle this.

String input

Add -S/--string argument for specifying input data as string on the command line instead of as file

PNG / PBM Choice

Re-instate the ability to render images to PNG format
PBM format is the default

Refactor for libsaxbospiral v0.21

• Swapped PNG output for PBM for now (this is easier to test)
• Also improved display of command-line options glossary

Save Your Progress

Now sxbp can optionally save the progress it's made on generating the spiral every x number of lines.
This means if the program is terminated or killed mid-solve, you'll most likely be able to pick up from where you last left off

OH NOES I FORGOT THE LICENSE FILE

#Hotfix - Adds the LICENSE file!

Open-Source

Yayy! Open-sourced!

Version the first

Initial version, imported from v0.14.0 of saxbospiral.