Its defaults are to unescape within single quotes, and escape within double quotes and here-docs. Right now, it leaves everything as-is, which means our code is inconsistent and need not be. Further, although dealing with complex regular expressions will never be easy, I find it much easier to figure out what's going on when superfluous back-slashes are removed.
These changes were all made automatically using the "fix" script, so should be reliable. They, of course, pass all unit tests.
Fix#4319. PR #3495 allowed Mpdf and Tcpdf to handle hidden rows and columns. The handling is a little off when merged cells are part of the output. The fix for Mpdf is pretty straightforward. Tcpdf is a little more convoluted. Dompdf and Html do not require a change. Unit tests are added for the same scenario for all of Mpdf, Tcpdf, Dompdf, and Html.
oleibman