[README] updates for Kodi
Merge pull request #5606 from yanniks/readmeother

README fixes and rebranding
[rbp/omxplayer] When opening a stream don't try to update gui so often
[ffmpeg] Speed up wtv index creation

The index creation is O(N^2) with number of entries (typically thousands).
On a Pi this can take more than 60 seconds to execute for a recording of a few hours.

By replacing with an O(N) loop, this takes virtually zero time
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
[omx] Report decoded image name
logging: Add microsecond timer to log messages
videoplayer: adapt lateness detection and dropping to buffering
video player: present correct pts to user for a/v sync (after buffering in renderer)
[hifiberry] Hack: force it to be recognised as IEC958 capable to enable passthrough options
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 vertices rather than only CGUIFontTTFBase::m_vertex
Add a cache of font glyph bounding box vertices.

This is implemented as a template because ultimately we will key on different
parameters and store values of different types, depending upon whether we
have a GLES or non-GLES backend, and for GLES, whether or not the currently
applicable transformation matrices permit the use of hardware clipping.
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.