Add proper ordering of include statements

The include statements are ordered from local to global with allways a blank
line between the blocks.

.clang-format

@@ -37,7 +37,22 @@ DerivePointerAlignment: false
 DisableFormat: false
 ExperimentalAutoDetectBinPacking: false
 FixNamespaceComments: true
-IncludeBlocks: Preserve
+IncludeBlocks: Regroup
+IncludeCategories:
+  - Regex:           '^("|<)Cbm'
+    Priority:        1
+  - Regex:           '^("|<)Fair'
+    Priority:        2
+  - Regex:           '^("|<)T'
+    Priority:        3
+  - Regex:           '^("|<)boost'
+    Priority:        4
+  - Regex:           '^<.*[^\.h]>'
+    Priority:        5
+  - Regex:           '^<.*>'
+    Priority:        6
+  - Regex:           '.*'
+    Priority:        7
 IndentCaseLabels: true
 IndentPPDirectives: None
 IndentWidth: 2