Include Catch2 library

.gitmodules

+[submodule "lib/Catch2"]
+	path = lib/Catch2
+	url = https://github.com/catchorg/Catch2.git

.idea/misc.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="CMakeWorkspace" PROJECT_DIR="$PROJECT_DIR$" />
+  <component name="CidrRootsConfiguration">
+    <sourceRoots>
+      <file path="$PROJECT_DIR$/inc" />
+      <file path="$PROJECT_DIR$/src" />
+    </sourceRoots>
+    <libraryRoots>
+      <file path="$PROJECT_DIR$/lib" />
+    </libraryRoots>
+  </component>
 </project>
\ No newline at end of file

.idea/vcs.xml

@@ -2,5 +2,6 @@
 <project version="4">
   <component name="VcsDirectoryMappings">
     <mapping directory="$PROJECT_DIR$" vcs="Git" />
+    <mapping directory="$PROJECT_DIR$/lib/Catch2" vcs="Git" />
   </component>
 </project>
\ No newline at end of file

Catch2 @ 77f29c2f

+Subproject commit 77f29c2f1cde8bd2e17f06cc04092b990d2acc2c