COMP: Fix build error when building on MacOSX 10.8/10.9. Issue #3405

This commit updates the python build system and ensure tk can be configured
when X11 header and libraries are in non-system location.

Python build system changes:

$ git shortlog 3c5864f2..47845 --no-merges
Jean-Christophe Fillion-Robin (12):
      Update .gitignore
      README: Re-organize README using markdown
      README: Associate Apache 2.0 License
      README: Update curl command to follow redirect
      README: Add instruction to check MD5 sum of the downloaded source package
      README: Add instruction to extract Python source archive
      README: Reference license file using relative link
      README: Format list of CMake options
      Display system processor
      Fix get_target_property warning related to non existent target
      Fix readline build error occurring when targeting MacOSX SDK 10.4
      Find X11 library and header to fix tkinter compile error. Fixes #33

Matt McCormick (3):
      Update Python version in README 2.7.1 -> 2.7.3.
      Support build for Linux/ARM.
      Reformat README from Markdown to reStructuredText.

Yann Collette (2):
      Simplify handling of python version introducing PY_VERSION CMake variable
      Fix failed uint{32,64}_t / int{32,64}_t detection on some platforms.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23608 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Fix OpenIGTLinkIF performance issue with PlusRemote. Issue #3813

$ git shortlog fb1a29..2ffd26 --no-merges
Andras Lasso (1):
      ENH: Prevent continuous changing of connector node state while waiting for connection

Jean-Christophe Fillion-Robin (2):
      STYLE: Remove end-of-line spaces
      COMP: Fix uninitialized variable warning in vtkIGTLToMRMLTrajectory.

Co-authored-by: Andras Lasso <lasso@queensu.ca>

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

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23609 3bd1e089-480b-0410-8dfb-8563597acbee
COMP: Do not choke on extension description containing semi-colon.

This commit fixes the following error:

CMake Error at /path/to/Slicer/CMake/UseSlicerMacros.cmake:92 (string):
  string sub-command LENGTH requires two arguments.
Call Stack (most recent call first):
  /path/to/Slicer-build/UseSlicer.cmake:392 (slicer_setting_variable_message)
  CMakeLists.txt:17 (include)

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23610 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Legacy module OtsuThresholdImageFilter needed by EMSegment. Issue #3815

This commit fixes a regression introduced by r23598 which removed
the source of OtsuThresholdImageFilter. This ensures EMSegment will
work as expected by integrating the source of the CLI as a
remote module [1].

[1] http://wiki.slicer.org/slicerWiki/index.php/Documentation/Nightly/Developers/Build_system/Remote_Module

For future reference, the EMSegment test
"EMSeg_SlicerCommonInterfaceTestGeneral" was failing with:

// ---------------
[...]
Test 7 : PreprocessingBiasFieldCorrection
ERROR: In /home/kitware/Dashboards/Nightly/Slicer-0-build/EMSegment/vtkSlicerCommonInterface.cxx, line 609
vtkSlicerCommonInterface (0x226d940): Could not find path to OtsuThresholdImageFilter

ERROR: In /home/kitware/Dashboards/Nightly/Slicer-0/Libs/MRML/Core/vtkMRMLVolumeArchetypeStorageNode.cxx, line 367
vtkMRMLVolumeArchetypeStorageNode (0x235fd00): ReadData: Cannot read file as a volume of type Volume[fullName = /tmp/EMSD1388245976wJ71mE/mask.nrrd]
    Number of files listed in the node = 0.
    File reader says it was able to read 0 files.
    File reader used the archetype file name of /tmp/EMSD1388245976wJ71mE/mask.nrrd []
[...]
// ---------------

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23611 3bd1e089-480b-0410-8dfb-8563597acbee