Clean up SPS extension code

See merge request !2186

Fix #1487: look for slice boundaries, not tile boundaries

See merge request !2185

Fix #1536: fix computation of number of explicit slice heights

See merge request !2184

Fix #1532: use correct parameter name

See merge request !2183

Fix #1519: preserve pel fraction when clipping MV

See merge request !2182

Fix #1535: don't use deprecated std::unary_function

See merge request !2179

m_videoIOYuvSEIFGSFile may be used without being initialized after !2132

See merge request !2181

fix compilation with gcc 11: 'misleading-indentation' error after !2177

See merge request !2180

Fix variable names

See merge request jvet/VVCSoftware_VTM!2177

Fix indentation and braces

See merge request jvet/VVCSoftware_VTM!2178

Remove T0196_SELECTIVE_RDOQ macro

See merge request jvet/VVCSoftware_VTM!2176

Fix indentation and braces

See merge request jvet/VVCSoftware_VTM!2174

Fix indentation and braces, improve readability

See merge request jvet/VVCSoftware_VTM!2173

Fix variable names

See merge request jvet/VVCSoftware_VTM!2172

Remove unused macro

See merge request jvet/VVCSoftware_VTM!2175