PERF: couple of speed up improvements for QuadEdgeMesh processing

In QuadEdgeMeshBoundaryEdgesMeshFunction::Evaluate(), change a local
container from std::list<> to std::set<> to improve performance of removing
elements.

In QuadEdgeMesh, make use of GetElementIfIndexExists to avoid doing
too many ::find on the MapContainer.

Change-Id: Ic76674c64c3959f527e68b6c0ce9893deb0e1155
STYLE: Enforce using ITK macros when available

During careful review of this calss, some ivars were identified
that could be removed and made local variables of one function.

Identified where a pointer could be made const.

Prefer initialization to assignment for class constuctor.

Logic for printing message about too many interations was moved
to the parent class where the other termination messages are appended
to build up the message string.

Change-Id: I4767db52c0979c85bdf1a482d809e30aa6d1191c
Merge topic 'SpeedUpMeshBoundary'

e5af98c PERF: couple of speed up improvements for QuadEdgeMesh processing
Merge topic 'LBFGSBOptimizerDebug'

71e9fa1 STYLE: Enforce using ITK macros when available
BUG: Using CMake variable in external builds with autoconf environment

Previously, the external projects of FFTW, SWIG and PCRE were affected
by environmental variable such as CC, CXX, CFLAGS etc. The could be
tested by setting CXX=/dev/null in the environment. Additionally,
these setting could change from when cmake was first run to when the
external project was (re)configured and compiled.

Now, the environment variable which effect the autoconf are not set in
via the "env" command before configuration.

Change-Id: Ie2d4f43c10d40186062a2e2917eff26b03b9815c
BUG: initialize InverseCovariance size with degenerate matrix

This patch fixes a segfault with VectorConfidenceConnected when used
with VectorImages and only one initial seed. This was caused by an
inverse matrix not being initialized correctly for variable length
measurement vectors.

Change-Id: I81bd2c9afe35f726d552c08849dd3c80710bca05
Merge topic 'FFTWExternalInEnviroment'

da4ce96 BUG: Using CMake variable in external builds with autoconf environment
Merge topic 'VectorConfidenceConnectedInvCovarSegfault'

b07b051 BUG: initialize InverseCovariance size with degenerate matrix