Update docs on Builders, Scanners, Environment

Environment Base docstrings tweaked.
Internal _update_onlynew added: like _update but update the env "dict"
  only with items that are not already in the internal dict: intent
  is to simplify numbers of "if FOO not in env: # set env[FOO]" in tools.
  There are no clients of this at this time.
Tweak BUILDERS cvar description
Add known keyword args accepted by Environment(), and pointer to
  the broken out Construction Environments section where these are described.
Add missing "name" keyword to template for Scanners()
Construction Environments: uncommented the note that setting a cvar after
  Environment() call do not always take effect - the question still
  remains how the user can tell that's the case.
Construction Environments - paragraphs for the other Environment kwargs
  with pointers to the sections that describe them.
A little clarification of use of None in Variables() call, plus
  be explicit about the default if Variables called with no args.
Mention that the default name of a Scanner object is "NONE" if not set.

Signed-off-by: Mats Wichmann <mats@linux.com>

0 files changed, 0 insertions, 0 deletions