Allow escaping backslash with backslash in filters (#614) (#616)

* Allow escaping backslash with backslash in filters (#614)

* Add test

* Strengthen test conditions

Co-authored-by: Salvage <29021710+Saalvage@users.noreply.github.com>
diff --git a/examples/all_features/CMakeLists.txt b/examples/all_features/CMakeLists.txt
index 3f4c837..4d2fe1b 100644
--- a/examples/all_features/CMakeLists.txt
+++ b/examples/all_features/CMakeLists.txt
@@ -89,6 +89,7 @@
 # -order-by=name to avoid different output depending on the compiler used. See https://github.com/doctest/doctest/issues/287
 doctest_add_test(NAME filter_2        COMMAND $<TARGET_FILE:all_features>   -tse=* -nv -order-by=name) # should filter out all + print skipped
 doctest_add_test(NAME filter_3        ${common_args} -sc=from*,sc* -sce=sc2 -sf=*subcases*) # enter a specific subcase - sc1
+doctest_add_test(NAME filter_4        ${common_args} -ts=*\\, -tc=*\\: -sc=*\\\\\\,,*:) # escape stuff
 doctest_add_test(NAME order_1         ${common_args} -ob=suite -ns          -sf=*test_cases_and_suites*)
 doctest_add_test(NAME order_2         ${common_args} -ob=name               -sf=*test_cases_and_suites*)
 doctest_add_test(NAME order_3         ${common_args} -ob=rand               -sfe=*) # exclude everything for no output