The PatternSyntax enum had to be removed as QRegularExpression only
supports Perl-compatible regular expressions.

As QVariant's comparison operators were removed, a simplified
comparison is now done as a starting point, but should probably
be extended to support more types.

Fixes oKcerG#84
Fixes oKcerG#86

cmake: fix c++17 build requirement for msvc

I was getting the following error:

/usr/bin/ld: isle/3rdparty/SortFilterProxyModel/CMakeFiles/SortFilterProxyModel.dir/SortFilterProxyModel_autogen/mocs_compilation.cpp.o: relocation R_X86_64_PC32 against symbol `__asan_option_detect_stack_use_after_return' can not be used when making a shared object; recompile with -fPIC

And:

/home/mitch/dev/bgv/isle/3rdparty/SortFilterProxyModel/qqmlsortfilterproxymodel.cpp:1: error: In included file: "You must build your code with position independent code if Qt was configured with -reduce-relocations. "         "Compile your code with -fPIC (and not with -fPIE)."

Initially I fixed this with:

    set(CMAKE_POSITION_INDEPENDENT_CODE ON)

but was told the proper solution is to add the missing
target_link_libraries.