* Bulk replaced tabs with spaces
* Bulk removed trailing whitespace from lines
* Replaced c-style comments with c++-style comments in file banners
* Replace nested namespace definitions with single concise definitions (C++17), this keeps the indentation more manageable
* Cleanup ordering and spacing of include directives
* Bulk renaming of header file extensions from '.h' to '.hpp'.
* Update CODING-STYLE.md
* Update target_compile_features from cxx_std_11 to cxx_std_20.
* Refresh .clang-format file. Still needs a lot of tweaking.
QTableWidget was a major bottleneck for large merge sources (#217). This is because a QTableWidgetItem needed to be created for every field in every record of the merge data, whether they are being displayed or not. This was not a problem for small merge sources (only a few dozen records max), however for larger data sets this would severely affect performance and make the application unresponsive. QTableView only renders the fields and records currently visible.
Jaye Evins