Implement strict dependency semantics

This patch allows specifying a dependency as `strict`, e.g.:

  build-depends:
  - filename: element.bst
    strict: true

This allows finer tuning of projects which want to leverage
the non-strict build mode; dependencies which are statically
linked to, or who's content is otherwise included verbatim in
the resulting output, should be marked `strict` to ensure these
bits get reassembled if necessary when building in non-strict
mode.

This fixes #254

Change summary:

  o _loader/loadelement.pyx: Added 'strict' attribute to Dependency

  o _loader/types.pyx: Added 'strict' attribute to Dependency
    do the parsing work.

  o _loader/metaelement.py: Added 'strict_dependencies' list

  o _loader/loader.py: Resolve the 'strict_dependencies' list

  o element.py: Added __strict_dependencies list, and use this
    to conditionally use weak cache keys in place of names for
    the purpose of building the weak cache key (in the case of
    dependencies which are marked as strict).

0 files changed, 0 insertions, 0 deletions