COMP: OpenIGTLinkIF - Anticipate logic headers reorganization.

Soon, as a compilation speedup, the base class "vtkMRMLAbstractLogic"
will forward declared classes in its definition file.

This commit fix compilation issue that would have occurred following
integration of the topic "finetjul/Slicer@vtkmrmlabstractlogic-clean-includes-trunk"

Fixes #3493

Co-authored-by: Jean-Christophe Fillion-Robin <jchris.fillionr@kitware.com>

From: Junichi Tokuda <tokuda@bwh.harvard.edu>

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22712 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Fixed translation sliders in local coordinate reference mode.

In local coordinate reference mode the slider positions do not match
directly with the transformation matrix values.

Similarly to rotation sliders, only relative positions are set
with the sliders in local coordinate reference mode.

Fixes #3488

From: Andras Lasso <lasso@queensu.ca>

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22713 3bd1e089-480b-0410-8dfb-8563597acbee
STYLE: generalizing the template

Making the metadata more general so that it can be used as
a documentation template file.



git-svn-id: http://svn.slicer.org/Slicer4/trunk@22715 3bd1e089-480b-0410-8dfb-8563597acbee
COMP: Support Slicer_USE_SYSTEM_* option. Fixes #1739

<<<<< WORK IN PROGRESS - DO NOT INTEGRATE >>>>>>

On Ubuntu 13.10, the following options have been tested simultaneously:
  -DSlicer_USE_PYTHONQT_WITH_OPENSSL:BOOL=ON
  -DSlicer_USE_SYSTEM_python:BOOL=ON
  -DSlicer_USE_SYSTEM_DCMTK:BOOL=ON
  -DSlicer_USE_SYSTEM_LibArchive:BOOL=ON
  -DSlicer_USE_SYSTEM_curl:BOOL=ON

The associated system packages have been installed using:
  sudo apt-get install libssl-dev \
    libdcmtk-dev \
    libarchive-dev \
    libpython2.7-dev \
    libcurl4-openssl-dev

This commit also add support for:
  -DSlicer_USE_SYSTEM_ITKv4:BOOL=ON
COMP: ExternalProject - Rename python variables with a slicer independent name
COMP: Set (tcl|tk)_LIBRARY variable into tcl external project