* external build framework macro and cmake_external rule
* declare deps headers as inputs as well; correct sed expression
* use symlinking instead of copying, filter duplicates
* correct detect root
* corrections for copying tools and include directories
* correct review comments
* provide a way to pass modified attributes to the framework function
create a function that creates a dict from ctx.attr,
replaces/adds values and creates a resulting struct;
have mandatory attributes as mandatory parameters to this function
* correct review comments
* correct detect_root
* introduce parameter for passing user defined link options
* add documentation, define default static library to be built
* correct/improve documentation
* more correct gathering headers and include directories from dependencies
* correct review comments
* correct passing transitive link options
irengrig