make it java11 compatible

[erwindon]

see #142

[erwindon]

@petternordlander
the files in src/deb indicate the build of a Debian package, but it looks incomplete.
I just updated the Depends: clause in src/deb/control/control to include all currently known/suitable java-runtimes, i.e. 11 through 21
how can I test that?

[northlander]

@erwindon thanks, will have a look this afternoon.

I must admit that I haven't tested the Debian part at all, a contribution by a Debian user. Would be nice to have it in some Debian/Ubuntu repo but I guess it's more effort than pay off. Perhaps we should just remove it.

[erwindon]

That is very useful information on the context.
I have enough knowledge on Debian style packages to get this working. Already created a local Debian VM in VirtualBox for this.
I'll just add a few practical changes in this PR to be able to actually create a deb package, install it locally and run it.

[erwindon]

no matter how popular the debian package of 'a' might become, the name 'a' as package name is never allowed. see https://www.debian.org/doc/debian-policy/ch-controlfields.html, where section 5.6.1 states that "[package names] must be at least two characters long and must start with an alphanumeric character."
I'll use 'fmtn-a' as debian package name (but feel free to suggest an even better one!)

[erwindon]

I took one Debian specific file out of the first commit.

The second commit has all the Debian specific stuff in it:

• added script to build the DEB package; and
• fixed shell script (original name bin.sh, now a.sh) to start a; and
• moved file control to proper location; filled the placeholders that it still had; and
• set the package dependencies to java11+; the headless edition is sufficient.

verified Debian package by building+installing it --> Unix command a now shows the usage-text.

[erwindon]

@northlander
(when) do you have time to review this?

[northlander]

Awesome work @erwindon !