Update tcl to use add_plugin
fix warning and improve error message

(thanks to R.P.)
Merge pull request #121 from easyxtarget/add_plugin-update

Update tcl to use add_plugin
added benchmark frontend generator
fix empty value handling + improve installation
add fallback/override metadata for contextual values
avoid code duplication for dynamic context
add dynamic context + tests
improve error message in exception
clean up correctly
fix benchmark.ini
remove benchmark.ini

because its not used within this repo
fix default bug

fix handling of empty strings
better handling of none type for nested frontends
fix compiler warnings in generated code
allow to change default plugins

constants plugin missing
optimize lookup by reusing the key
implement cascading search for ksLookup

needed for previous optimization
optimize ksLookupBySpec
optimize ksLookup
deprecate ksLookupByName

optimize ksLookup
remove duplication of cascading in ksLookupByName