Move dependencies in 'external' directory and pdate git submodules

external/Catch2/.clang-format

@@ -0,0 +1,45 @@
+---
+Language: Cpp
+Standard: c++14
+
+# Note that we cannot use IncludeIsMainRegex functionality, because it
+# does not support includes in angle brackets (<>)
+SortIncludes: true
+IncludeBlocks: Regroup
+IncludeCategories:
+  - Regex: <catch2/.*\.hpp>
+    Priority: 1
+  - Regex: <.*/.*\.hpp>
+    Priority: 2
+  - Regex: <.*>
+    Priority: 3
+
+AllowShortBlocksOnASingleLine: Always
+AllowShortEnumsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: All
+AllowShortIfStatementsOnASingleLine: WithoutElse
+AllowShortLambdasOnASingleLine: Inline
+
+AccessModifierOffset: "-4"
+AlignEscapedNewlines: Left
+AllowAllConstructorInitializersOnNextLine: "true"
+BinPackArguments: "false"
+BinPackParameters: "false"
+BreakConstructorInitializers: AfterColon
+ConstructorInitializerAllOnOneLineOrOnePerLine: "true"
+DerivePointerAlignment: "false"
+FixNamespaceComments: "true"
+IndentCaseLabels: "false"
+IndentPPDirectives: AfterHash
+IndentWidth: "4"
+NamespaceIndentation: All
+PointerAlignment: Left
+SpaceBeforeCtorInitializerColon: "false"
+SpaceInEmptyParentheses: "false"
+SpacesInParentheses: "true"
+TabWidth: "4"
+UseTab: Never
+AlwaysBreakTemplateDeclarations: Yes
+SpaceAfterTemplateKeyword: true
+SortUsingDeclarations: true
+ReflowComments: true