Add .clang-format and .clang-tidy

This enables files for checking against the
[LMMS coding conventions](https://github.com/LMMS/lmms/wiki/Coding-conventions).

There is no strategy for automatic testing yet.

.clang-format

@@ -0,0 +1,65 @@
+---
+# Language
+Language:        Cpp
+Standard:        Cpp11
+
+# Identation
+TabWidth:        8
+UseTab:          Always
+IndentWidth:     8
+ColumnLimit:     80
+
+# Identation detail
+AlignAfterOpenBracket: DontAlign
+ContinuationIndentWidth: 8
+BreakConstructorInitializers: AfterColon
+ConstructorInitializerIndentWidth: 8
+ConstructorInitializerAllOnOneLineOrOnePerLine: false
+BinPackParameters: true
+BinPackArguments: false
+AlignOperands: false
+AlignEscapedNewlines: DontAlign
+AccessModifierOffset: -8
+
+# Includes
+IncludeBlocks:   Regroup
+IncludeCategories:
+  # the "main header" iplicitly gets priority 0
+  # system headers
+  - Regex:           '^<[^>]+>$'
+    Priority:        1
+  # non-system headers
+  - Regex:           '.*'
+    Priority:        2
+SortIncludes:    true
+
+# Spaces
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeParens: ControlStatements
+SpacesInAngles:  false
+SpacesInCStyleCastParentheses: false
+SpacesInParentheses: false
+
+# Brace wrapping
+# Not directly mentioned in the coding conventions,
+# but required to avoid tons of auto reformatting
+BreakBeforeBraces: Custom
+BraceWrapping:
+  AfterClass: true
+  AfterControlStatement: true
+  AfterEnum: true
+  AfterFunction: true
+  AfterNamespace: true
+  AfterStruct: true
+  AfterUnion: true
+  AfterExternBlock: true
+  BeforeCatch: true
+  BeforeElse: true
+  IndentBraces: false
+  SplitEmptyFunction: true
+  SplitEmptyRecord: true
+  SplitEmptyNamespace: true
+
+
+...
+

.clang-tidy

@@ -0,0 +1,33 @@
+---
+Checks:          'readability-identifier-naming,readability-misleading-indentation,readability-simplify-boolean-expr,readability-braces-around-statements,bugprone-macro-parentheses,bugprone-macro-repeated-side-effects'
+WarningsAsErrors: ''
+HeaderFilterRegex: '' # don't show errors from headers
+AnalyzeTemporaryDtors: false
+FormatStyle:     none
+User:            user
+CheckOptions:    
+  - key:             readability-identifier-naming.ClassCase
+    value:           CamelCase
+  - key:             readability-identifier-naming.EnumCase
+    value:           CamelCase
+  - key:             readability-identifier-naming.TypedefCase
+    value:           CamelCase
+  - key:             readability-identifier-naming.UnionCase
+    value:           CamelCase
+  - key:             readability-identifier-naming.StructCase
+    value:           CamelCase
+  - key:             readability-identifier-naming.UnionCase
+    value:           CamelCase
+# not yet working, as it currently applies both for static and object members
+# - key:             readability-identifier-naming.MemberPrefix
+#   value:           'm_'
+  # currently only working for local static variables:
+  - key:             readability-identifier-naming.StaticVariablePrefix
+    value:           's_'
+# not yet working
+# - key:             readability-identifier-naming.VariableCase
+#   value:           camelBack
+  - key:             readability-identifier-naming.FunctionCase
+    value:           camelBack
+...
+