Apply default styling for lexers with no grammar; LexLPeg.cxx
This should reduce number of calls for styling, particularly for the text lexer.
Improved performance for lexers with no fold rules; lexers/lexer.lua
When resetting fold levels, do not make a copy of each line's contents.
Processing long lines was particularly expensive.
Updated CHANGELOG.md.
Added tag scintillua_3.5.1-1 for changeset c7521631ebec