Clean up legacy names in source code

[fschopp]

• Remove MutableSimpleNameable and just have SimpleName implement BareSimpleNameable?
• RuntimeAnnoatedExecutionTrace should be renamed. Possibly just RuntimeTrace.
• Rename subproject cloudkeeper-maven-bundle-loader to something more accurate
• 'proxy module' should arguably be renamed to 'invocation module' or even 'module invocation'
• Possibly replace 'declaration' by 'definition'. No need for a distinction in CK.
• Possibly remove 'bare' prefix from model interfaces (need to be careful about name clashes with DSL, though)
• Decide for using 'workflow' or 'dataflow' consistently
• Use 'executor' and 'interpreter' consistently
• runtime context vs. runtime state
• executable vs. simple-module definition