Debug flags

[heribender]

Hi

I implemented some enhancements/bugfixes:

• dealing with the debug flags. Until now they were hardcoded, I added the possibility to define them by SysEnvVars. -- static method initDebugFlags added to CommPortIdentifier, RXTXCommDriver and RXTXPort
• Searching for gnu.io.rxtx.properties: EnvVar "java.ext.dirs" may return more than one dir
• build.gradle: -- added the possibility to overload the build.properties by a user.build.properties -- introduced the new build property jar.noversion. If set to true, the built jar file does not contain a version.
• README.md enhanced: Added detailled description of the recognized environment variables starting with "gnu.io.".

I would love if you would merge this changes to the HEAD.

BTW: I had to do the changes (and tests) on a branch of Version 3.12.1 (commit c9f9f84e434115739d6ee2565829761c60624752), because later commits contain changes which use forbidden java classes ("com.sun." package) which are not present in a java 8 JRE. You should re-evaluate these changes by finding another possibility to recognize the comports on windows system without the need of using these forbidden packages.

[madhephaestus]

Pull from master and merge the conflicts into this branch?

[heribender]

Yes. for my changes I branched the version 3.12.1 (commit c9f9f84). The conflicts are only in the import statements, nowhere in the code. Thus you can edit the conflicts by overtaking my version.

[heribender]

BTW: I would resolve it by myself, but I do not know how. Clicking on above "Resolve conflicts" button leads me to a page which only displays the conflicts, but does not allow to resolve it. Maybe because I have no write access to the main repo?

[madhephaestus]

Reopen if your branch is mergable