GUIFontTTFDX: prevent crash on unallocated texture or unavailable Direct3D device
CGUIFontTTFGL::Begin: prevent crash on unallocated texture
CGUIFontTTFDX::ReallocTexture: Don't try to copy from empty texture
CGUIFontTTFGL::ReallocTexture log warning when allocated texture smaller than requested
CGUIFontTTFBase::CacheCharacter: free allocated glyph on error
GUIFontTTF: move m_textureScale calculation to right places
CGUIFontTTFBase::CacheCharacter: correctly process empty glyphs (spaces)
Empty glyphs (spaces) has zero width and if empty glyph is first cached letter than texture isn't allocated and function complains about "no texture".
CGUIFontTTFBase: make "spacing_between_characters_in_texture" const
CGUIFontTTFBase::RenderCharacter don't try to render character if character bitmap is empty
CGUIFontTTFBase: don't use "printf" for errors
CGUIFontTTFBase: Use real function names for log instead of hardcoded
Merge pull request #3044 from Karlson2k/fonts_handling_01

Set of fixes for font processing