Feature: featureless make should support custom source paths in data/build/settings.

Feature: featureless make should support custom source paths in data/build/settings.

The standard path is used by the featureless linux library.
If any other project, such as bzip2, has its own directory structure provide a way to more likely support that when using the build operation.

This is not intended to handle all possible cases.
This is only intended to handle simple cases such as with bzip2.

For more complex builds the fakefile and the make operation should instead be used.

This adds a path_standard setting that is a yes/no boolean for designating if/when to follow the standard source path structure or not.
When this is 'yes', then the standard sources path such as 'sources/c/' is used or when -S/--sources is supplied then the path would be 'XXX/c/' when using "-S xxx/" as an example.
When this is 'no', then the sources path specified by a new setting 'path_sources' is used but when -S/--sources is supplied then the path would be 'XXX/' when using "-S xxx/" as an example.

The result of this change moves the "sources/" directory from required to optional.
This directory is no longer checked for during the check required directories process.

The bootstrap.sh script is exclusively intended to be used for compiling the featureless linux library.
Therefore, the 'path_standard' and 'path_sources' are unimplemented within that script (beyond being defined in the variable list).