Release for review of initial development

• support for packs node in cproject and clayer files
• support for IAR linker script extension .icf
• format RTE context specific subfolder _<build-type>_<target-type>
• added --clayer-path option for list layers
• added for-board and for-device nodes in clayers
• added --debug option for increased verbosity
• added $Pname$ access sequence
• added output filenames customization handling
• added gendir component instance attribute
• added --toolchain command line option for compiler selection
• reworked toolchain registration