More export templates

Summary

This MR brings more template exports.

Rationale

This is part of story #1649 (closed).

Implementation Details

CMake mechanism to export all symbols

I had a problem with the export of ITK classes : they are not defined with a proper export macro as we try to do now with extern templates. By default, the compilation of shared libraries in OTB uses -fvisibility=hidden so that symbols are hidden by default (unless explicitely exported). In order to make ITK symbols visible in OTB shared libraries I had to compile them into a dedicated shared lib, and to disable the hidden setting. This is done when declaring the module, with the option EXPORT_ALL, for example, in OTBITK module:

otb_module(OTBITK
  ENABLE_SHARED
  EXPORT_ALL
  DEPENDS
    ...

New modules with extern templates

The exports in OTBImageBase and OTBImageIO have been enhanced.

More extern template have been added, in modules:

• OTBCommon
• OTBObjectList
• OTBStreaming
• OTBVectorDataBase
• OTBTransform
• OTBITK
• OTBImageExport (new module for ITK templates using Image and VectorImage)
• OTBImageManipulation
• OTBStatistics
• OTBVectorDataManipulation
• OTBVectorDataIO

Move implementations into cxx

The implementation of some classes has been moved to a dedicated .cxx, for instance :

• VectorDataFileWriterException
• ImageKeywordlist
• QtWidgetParameterBase

Additional notes

The export of itkDynamicCastInDebugMode functions is done in module OTBImageExport.

TODO : show some figure regarding improvements on build time and binaries size.

TODO : add comments proposed by @poughov

Copyright

The copyright owner is CNES and has signed the ORFEO ToolBox Contributor License Agreement.

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