Added export methods for PagedLOD. Fixed missing headers in CMakeLists.txt
Updated the osgjs plugin to serialize user defined center and center mode
Fixes pretransform visitor with shared arrays
Adds allowDrawArray attribute in TriStripVisitor
[#75094726] Splits osgjs plugin into gles (reader) and osgjs (writer) plugins

* osgjs plugin should only serve for output serialization;
* gles plugin should handle geometry processing and optimization for webgl.
[#75094726] Adds 'triStripMinSize' option for gles pseudo-loader
[#75094726] Fixes mergeTrianglesStrip in gles pseudo-loader

* avoid unnecessary degenerated triangles
* insert strip at the beginning of PrimitiveSetList to benefit more from
  vertex pretransform
[#75094726] Enables gles as a pseudo-writer

In order to avoid issues with osg::Optimizer (such as merging splitted geometries),
it might be practical to use gles as a pseudo-loader rather than a pseudo-loader.
[#75095064] Refactors GLES pseudo-loader

* refactors primitive functors to avoid duplicates & obsolete code
* refactors WireframeVisitor: fixes some primitives indexation and enable to
  store an inlined wireframe; note that wireframe handling has to be managed by
  optimizer visitors
* refactors GeometryIndexSplitVisitor to handle lines
* Adds maxIndexValue option for debug purposes
* uses GeometryUniqueVisitor for DRY
* OpenGLESGeometryOptimizer is no longer a visitor but a conductor calling the
  desired gles optimization visitors (and renames visitor files correctly)
* as a consequence, the scene is now traversed by each visitor which will
  induce longer processing timings
* all visitors work on DrawElementsUInt; osgjs will offer a visitor to compact
  integers buffers
* cleans some trailing space
* fixes some compiler warnings
[#75095926] Adds option for osgjs to dump buffer data in specific binary files
[#75095926] Adds serialization of non-string UserValues in osgjs
[#75095926] Adds VecX(u)iArrayType in osgjs serialization
[#75095926] Adds optional varint encoding in osgjs
[#75095926] Updates osgjs tangent space handling
[#75095926] Updates osgjs index serialization

* uses correct types when serializing
* adds CompactBufferVisitor to use smallest possible types for integer buffers
Fixes pretransform visitor with shared arrays
Adds allowDrawArray attribute in TriStripVisitor
[#75094726] Splits osgjs plugin into gles (reader) and osgjs (writer) plugins

* osgjs plugin should only serve for output serialization;
* gles plugin should handle geometry processing and optimization for webgl.
[#75094726] Adds 'triStripMinSize' option for gles pseudo-loader
[#75094726] Fixes mergeTrianglesStrip in gles pseudo-loader

* avoid unnecessary degenerated triangles
* insert strip at the beginning of PrimitiveSetList to benefit more from
  vertex pretransform