Code generation fails if clang-format-6.0 is missing

[corot]

Describe the bug

Well, not exactly a bug, but I didn't see in the instructions that I need to install a particular clang version. Would be much better to either:

• make clang optional and show a warning
• request to install clang but use any version >= 6.0 available

$ ./generate.sh ../alica_ros_turtlesim/alica/
/home/jorge/rapyuta_ws/alica_tutorials/src/alica-supplementary/alica_designer_runtime
ERROR StatusLogger No log4j2 configuration file found. Using default configuration: logging only errors to the console. Set system property 'org.apache.logging.log4j.simplelog.StatusLogger.level' to TRACE to show Log4j2 internal initialization logging.
PluginManager: alica-plan-designer-fx-default-plugin-0.1.1-SNAPSHOT.1.jar
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by de.unikassel.vs.alica.generator.plugin.PluginManager (file:/home/jorge/rapyuta_ws/alica_tutorials/src/alica-supplementary/alica_designer_runtime/codegen/PlanDesignerFX-Codegeneration-0.1.1.1328.jar) to method java.net.URLClassLoader.addURL(java.net.URL)
WARNING: Please consider reporting this to the maintainers of de.unikassel.vs.alica.generator.plugin.PluginManager
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
12:44:26.773 [main] ERROR de.unikassel.vs.alica.generator.cpp.CPPGeneratorImpl - An error occurred while formatting generated sources
java.io.IOException: Cannot run program "/usr/bin/clang-format-6.0": error=2, No such file or directory
	at java.lang.ProcessBuilder.start(ProcessBuilder.java:1128) ~[?:?]
	at java.lang.ProcessBuilder.start(ProcessBuilder.java:1071) ~[?:?]
	at java.lang.Runtime.exec(Runtime.java:592) ~[?:?]
	at java.lang.Runtime.exec(Runtime.java:416) ~[?:?]
	at java.lang.Runtime.exec(Runtime.java:313) ~[?:?]
	at de.unikassel.vs.alica.generator.cpp.CPPGeneratorImpl.formatFile(CPPGeneratorImpl.java:469) [PlanDesignerFX-Codegeneration-0.1.1.1328.jar:?]
	at de.unikassel.vs.alica.generator.cpp.CPPGeneratorImpl.createDomainBehaviour(CPPGeneratorImpl.java:382) [PlanDesignerFX-Codegeneration-0.1.1.1328.jar:?]
	at de.unikassel.vs.alica.generator.Codegenerator.generate(Codegenerator.java:98) [PlanDesignerFX-Codegeneration-0.1.1.1328.jar:?]
	at de.unikassel.vs.alica.generator.StandaloneCodegenerator.main(StandaloneCodegenerator.java:68) [PlanDesignerFX-Codegeneration-0.1.1.1328.jar:?]
Caused by: java.io.IOException: error=2, No such file or directory
	at java.lang.ProcessImpl.forkAndExec(Native Method) ~[?:?]
	at java.lang.ProcessImpl.<init>(ProcessImpl.java:340) ~[?:?]
	at java.lang.ProcessImpl.start(ProcessImpl.java:271) ~[?:?]
	at java.lang.ProcessBuilder.start(ProcessBuilder.java:1107) ~[?:?]
	... 8 more
Exception in thread "main" java.lang.RuntimeException: java.io.IOException: Cannot run program "/usr/bin/clang-format-6.0": error=2, No such file or directory
	at de.unikassel.vs.alica.generator.cpp.CPPGeneratorImpl.formatFile(CPPGeneratorImpl.java:472)
	at de.unikassel.vs.alica.generator.cpp.CPPGeneratorImpl.createDomainBehaviour(CPPGeneratorImpl.java:382)
	at de.unikassel.vs.alica.generator.Codegenerator.generate(Codegenerator.java:98)
	at de.unikassel.vs.alica.generator.StandaloneCodegenerator.main(StandaloneCodegenerator.java:68)
Caused by: java.io.IOException: Cannot run program "/usr/bin/clang-format-6.0": error=2, No such file or directory
	at java.base/java.lang.ProcessBuilder.start(ProcessBuilder.java:1128)
	at java.base/java.lang.ProcessBuilder.start(ProcessBuilder.java:1071)
	at java.base/java.lang.Runtime.exec(Runtime.java:592)
	at java.base/java.lang.Runtime.exec(Runtime.java:416)
	at java.base/java.lang.Runtime.exec(Runtime.java:313)
	at de.unikassel.vs.alica.generator.cpp.CPPGeneratorImpl.formatFile(CPPGeneratorImpl.java:469)
	... 3 more
Caused by: java.io.IOException: error=2, No such file or directory
	at java.base/java.lang.ProcessImpl.forkAndExec(Native Method)
	at java.base/java.lang.ProcessImpl.<init>(ProcessImpl.java:340)
	at java.base/java.lang.ProcessImpl.start(ProcessImpl.java:271)
	at java.base/java.lang.ProcessBuilder.start(ProcessBuilder.java:1107)
	... 8 more

To Reproduce
Just follow turtlesim tutorial

Expected behaviour
Code generation works with any clang version

[Dale-Koenig]

Switched alica to use clang-format-10, just need to up code generation repo default