Migrate from Catch to Doctest

This reduces the build times of the test suite by about two thirds in my
testing in another project.

Change-Id: I8a5da3aff0956796c718d13237d0620f48316029
Depends-on: https://gerrit.cesnet.cz/c/CzechLight/dependencies/+/1580
diff --git a/.clang-format b/.clang-format
index f9b078b..2a60aa0 100644
--- a/.clang-format
+++ b/.clang-format
@@ -4,7 +4,7 @@
 Standard: Cpp11
 Cpp11BracedListStyle: true
 IncludeCategories:
-  - Regex: '^"trompeloeil_catch.h'
+  - Regex: '^"trompeloeil_doctest.h'
     Priority:        1
   - Regex:           '^<'
     Priority:        2