CI: add clang-format as a tool

- update the style guide to require braces around blocks
 - add a clang-format file that is pretty close to the
   astyle configuration

.clang-format

@@ -0,0 +1,33 @@
+---
+BasedOnStyle: WebKit
+
+AlignAfterOpenBracket: Align
+AllowAllParametersOfDeclarationOnNextLine: 'false'
+AllowShortFunctionsOnASingleLine: Inline
+AllowShortIfStatementsOnASingleLine: 'false'
+AllowShortLoopsOnASingleLine: 'false'
+AlwaysBreakAfterDefinitionReturnType: All
+AlwaysBreakTemplateDeclarations: Yes
+BinPackArguments: 'false'
+BinPackParameters: 'false'
+BreakBeforeBraces: Allman
+BreakBeforeTernaryOperators: 'true'
+BreakConstructorInitializers: BeforeComma
+ColumnLimit: 120
+Cpp11BracedListStyle: 'false'
+FixNamespaceComments: 'true'
+IncludeBlocks: Preserve
+IndentWidth: '4'
+MaxEmptyLinesToKeep: '2'
+NamespaceIndentation: Inner
+PointerAlignment: Left
+ReflowComments: 'false'
+SortIncludes: 'true'
+SpaceAfterCStyleCast: 'false'
+SpacesBeforeTrailingComments: '2'
+SpacesInAngles: 'true'
+SpacesInParentheses: 'true'
+SpacesInSquareBrackets: 'true'
+Standard: Cpp11
+
+...

ci/HACKING.md

@@ -56,7 +56,7 @@ some PEP8 guidelines.
 * For pointer and reference variable declarations, put a space before the variable name
   and no space between the type and the `*` or `&`, e.g. `int* p`.
 * `for`, `if`, `else`, `while` and similar statements put the braces on the next line,
-  if the following block is more than one statement. Use no braces for single statements.
+  if the following block is more than one statement. Always use braces.
 * Function and class definitions have their braces on separate lines.
 * A function implementation's return type is on its own line.
 * `CamelCase.{cpp,h}` style file names.
@@ -86,9 +86,13 @@ MyClass::myMethod( QStringList list, const QString& name )
 }
 ```
 
-You can use the `ci/calamaresstyle` script to run
-[astyle](http://astyle.sf.net) on your code and have it formatted the right
-way.
+You can use `clang-format` (version 7) to have Calamares sources formatted
+the right way. There is a `.clang-format` file that specifies the details.
+In general:
+```
+    $ clang-format-7 -i -style=file <files>
+```
+`
 
 **NOTE:** An .editorconfig file is included to assist with formatting. In
 order to take advantage of this functionality you will need to acquire the