BUG: Fixed memory overusage in LandweberDeconvolutionImageFilter

Some of the internally generated intermediate images in the
FFTConvolution filter were being retained until the end of the
algorithm, leading to excessive memory usage.

Also, changed internal filters within the
LandweberDeconvolutionAlgorithm to use the number of threads used by
the filter, and released data were possible.

Change-Id: I2441fe883d7405f469be707dfdb4083d9cbb3ed3
COMP: Remove undefined complex types

http://www.cplusplus.com/reference/complex/complex/

Type of both the real and imaginary components of the complex number.  The
effect of instantiating a complex with a T other than float, double or long
double is undefined (certain library implementations may support it, but the
resulting code is non-portable).

http://stackoverflow.com/questions/11108587/why-does-abscomplexint-always-return-zero

According to the C++ ISO spec, §26.2/2:

The effect of instantiating the template complex for any type other than float,
double or long double is unspecified.

Change-Id: I470b22f8e50ac0206f20646e342f19f6ea127f14
Merge topic 'FixExcessiveMemoryUsage'

3ce16a4 BUG: Fixed memory overusage in LandweberDeconvolutionImageFilter
Merge topic 'some-osx-mavericks-corrections'

beb6f85 COMP: Remove undefined complex types