Fix issue with gdcm::ImageRegionReader not updating image meta data
Fix compilation with advanced options
Merge branch 'release'
List all possible targets generated by GDCM

We will only export those that are actual target. Fixes #317
Merge branch 'release'
Backport VTK6 changes from master onto release
Merge branch 'release'
Fixed trivial warning about dead 'return' statement
Fixed -Wunreachable-code-return warning that indicated bigger problem

clang warned that a trailing else was impossible; it was right because
a preceding 'if' was of the form:

 if (a == b || c)

instead of:

 if (a == b || a == c)

since 'c' is a non-zero constant, the 'if' was always true, making
the next 'else' impossible.
Merge branch 'release'
Prepare 2.4.2 release
handle PDF generation issue