Make catch a submodule so it can be updated more easily

.gitignore

@@ -60,7 +60,8 @@ proj/vs*/packages/
 .sconsign.dblite
 .sconsign.tmp
 build/
-deps/
+deps/lib/
+deps/include/
 
 # Generated NSIS script file
 pkg/win/data.nsi

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "deps/Catch2"]
+	path = deps/Catch2
+	url = https://github.com/catchorg/Catch2.git

proj/xc12/BoE.xcodeproj/project.pbxproj

@@ -2228,6 +2228,7 @@
 				GCC_WARN_UNUSED_VARIABLE = YES;
 				HEADER_SEARCH_PATHS = (
 					/opt/local/include,
+					"$(PROJECT_DIR)/../../deps/Catch2/single_include",
 					"$(PROJECT_DIR)/../../src/fileio/gzstream",
 					"$(PROJECT_DIR)/../../src/fileio/xml-parser",
 				);
@@ -2327,6 +2328,7 @@
 				GCC_WARN_UNUSED_VARIABLE = YES;
 				HEADER_SEARCH_PATHS = (
 					/opt/local/include,
+					"$(PROJECT_DIR)/../../deps/Catch2/single_include",
 					"$(PROJECT_DIR)/../../src/fileio/gzstream",
 					"$(PROJECT_DIR)/../../src/fileio/xml-parser",
 				);