Make anim system safer for threading

Remove usages of ANIM_unit_mapping_apply_fcurve in favor of
runtime scale factor apply.

There're still calls to ANIM_nla_mapping_apply_fcurve are
hanging around, they're the next t be cleaned up!

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@60998 954f8c5b-7b00-dc11-b283-0030488c597c
Project Pampa request: FCurves normalized display

Added two options to a header of FCurve editor:

- Normalize which makes it so every individual
  curve is fit into -1..1 space.

- Auto-normalize, which probably is to be called
  "Lock" which "locks" curve normalization scale.
  This is useful to prevent curves from jumping
  around when tweaking it.

It's debatable whether it need to be a button to
normalize curves n purpose only, and it's fully
depends on animator's workflow.

Here during Project Pampa we've got Francesco
who get used to auto-renormalization and Hjalti
who prefers locked behavior.

Docs are to be ready soon by Francesco.
Thanks Brecht for the review!

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@60999 954f8c5b-7b00-dc11-b283-0030488c597c