ESC/P isn't ESC/POS

[tresf]

After some troubleshooting with a client, we've identified that our wiki, website, sample.html and codebase incorrectly uses ESC/P in place of ESC/POS code and code examples. Although these languages are very similar, ESC/POS is a variation of ESC/P and uses many incompatible commands.

This is going to be some work to reverse, but here's the proposal:

• @lite1979 will test and then change the wiki documentation to reference ESC/POS in title and API examples
• @klabarge will patch all instances of this wording on our site and samples
• @tresf will patch the codebase

The plan is to phase out ESCP entirely and issue a soft console warning and select ESC/POS (ESC_POS) if used. Internally to the codebase, we'll get ride of ESCP and instead map it functionally to a new value ESC_POS. ESC/P (ESC_P) will be added as a new stub which will throw UnsuportedOperationException if provided. Moving forward with ESC/P features, we'll use the version with the slash for the API and the version with the underscore internal to the Java application.

Since the image command is the only command that uses this, we'll simply keep the old one around but update our samples and documentation to use the new ESCPOS.

[jass-trix]

@tresf So does it means that ESCP = ESCPOS?

[tresf]

QZ Tray will treat them the same, but it's technically wrong. ESC/P uses a different image syntax which we don't yet have coded but we'd welcome a PR for it. ESC/POS is technically what we support in our codebase. For 99% of users, ESCPOS is what should be provided and is backwards compatible with older QZ Tray versions.