adds GetTvShowSeasons
move AddSeason() public.
adds GetArt function to (video) scraper, allowing art to be fetched given the video identifier.
refresh season art if a new season is found that isn't recorded in the database yet. Fixes #14339
REMOVEME: updated thetvdb.com scraper to support art updates
dvdplayer: make sure we restore output timestamps for text based subs
omxplayer: make sure we restore output timestamps for text based subs
FIX: implement libcurl openssl thread-safe locking
Move the reference-counting of Begin and End calls from DX and GL source files into GUIFontTTF.cpp.
Convert CGUIFontTTFBase::m_vertex to be managed as a std::vector. Also retired CGUIFontTTFBase::m_vertex_count and CGUIFontTTFBase::m_vertex_size because these can be derived from vector member functions.
CGUIFontTTFBase::RenderCharacter can now append to arbitrary vectors of vertixes rather than only CGUIFontTTFBase::m_vertex
Add a cache of the vertices describing the position of characters after transformation
Lay the groundwork for hardware clipping.

For glScissor() to replace CGraphicContext::ClipRect, a necessary condition
is that no shear or rotation is introduced between the coordinate systems
they use; this depends upon the settings of the GUI matrix m_finalTransform
as well as the OpenGL model-view and projection matrices. These all remain
unchanged between paired calls of CGUIShader::OnEnabled and
CGUIShader::OnDisabled, so we scan the matrices in CGUIShader::OnEnabled to
see whether hardware clipping is possible.

Then, in CGUIFontTTFBase::RenderCharacter, we don't apply software clipping
in such cases. However, because vertices arising from multiple
CGUIFontTTFBase::DrawTextInternal calls (each of which often uses a different
clip rectangle) get lumped into the same vector, which only at the end is
passed to OpenGL for rendering, we need to wait a few commits before we can
actually apply hardware clipping. In the meantime, expect to see rendering
errors.
Increase font cache hit rate by keying on the fractional part of m_originX and m_originY *after* they have been through the graphics context's transformation matrix, plus the scale/rotation elements of the matrix, rather than the origin in the original frame of reference plus the complete transformation matrix. All vertices of individual glyph bounding boxes are a constant offset from this position, and when the fractional part of the translation is a match, the rounding of each vertex will be in the same direction; this permits us to calculate the desired vertices from the cached ones simply by adding the integer parts of the translations with no additional rounding steps.

Note that this requires that software clipping is *not* performed.
Rewrite of scrolling text code. Now advances the character index into the string at coarser intervals of several characters, with more use of the pixel offset being used instead. This enables better utilisation of the font vertex cache. It also makes motion smoother, because (possibly unintentionally) the previous code preferred to align the scroll offset with character boundaries. This would lead to uneven changes of position, especially when the width of the character currently being scrolled off the edge was only slightly more than an integral multiple of the scroll increment.
Alternate version
Move the application of the translation offsets into the GLES code. Still all pure software at this stage. Main change is in the data types at the interface between CGUIFontTTFBase and CGUIFontTTFGL. The old way (array of vertices in m_vertex) are retained in addition, for the sake`of cases that need to use software clipping on GLES, as well as for DX and GL support where the new scheme is not (yet?) used.
Rather than applying the translation offsets to the vertices, now applies them to the model view matrix from the top of the matrix stack and pushes it over to OpenGL. The vertices themselves are still all held client-side.
Enable hardware clipping
Move the vertex data across to a vertex buffer object just prior to drawing.