MAKESCENE: fix case for original image missing

Checking for a NULL original image seems more reasonable here.
style fix: use NULL for null pointers
style fix: don't use RefPtr::get()
Merge pull request #49 from Waldteufel/fix-original-missing

MAKESCENE: fix case for original image missing
MVE: Fixed TriangleMesh::delete_vertices()
MATH: Added MATH_SQRT_2PI, changed MATH_SQRT1_2 to MATH_1_SQRT_2, changed MATH_2_SQRTPI to MATH_2_SQRT_PI
MATH: Optimization for math::algo::fastpow()
Merge pull request #50 from Waldteufel/fix-style

Style fixes
APPS: Updated scene2pset to output confidences
MATH: Added MATH_SQRT_PI define
MVE: Removed depthmap_mesh_confidences() down-weighting exponent
DMRECON: Sanity check for empty embedding name
UMVE: Sanity checks before starting MVS
MVE: Removed verbose output while saving views
Merge branch 'master' of github.com:simonfuhrmann/mve
dmrecon: remove "scale == -1" feature

Don't reconstruct L0-L4 when scale is -1.
dmrecon: improve error handling

* skip view if embedding is missing, don't crash
* show errors in FancyProgressPrinter
UMVE: fix two segfaults

* move view == NULL check in start_dmrecon_job
* fix crash when job is cancelled twice
Merge pull request #51 from Waldteufel/dmrecon-error-handling

dmrecon: error handling
remove more RefPtr::get() calls