build: update coding-style settings

Update .editorconfig, and add .clang-format.

Note that current code does _not_ follow that, but we'll slowly get there.

.clang-format

@@ -0,0 +1,39 @@
+---
+AlignAfterOpenBracket: 'Align'
+AlignConsecutiveAssignments: 'false'
+AlignConsecutiveDeclarations: 'false'
+AlignConsecutiveMacros: 'true'
+AlignOperands: 'true'
+AlignTrailingComments: 'true'
+AllowAllArgumentsOnNextLine: 'false'
+AllowAllParametersOfDeclarationOnNextLine: 'false'
+AllowShortBlocksOnASingleLine: 'false'
+AllowShortCaseLabelsOnASingleLine: 'false'
+AllowShortFunctionsOnASingleLine: 'Inline'
+AllowShortIfStatementsOnASingleLine: 'false'
+AlwaysBreakAfterReturnType: 'All'
+BinPackParameters: 'false'
+BinPackArguments: 'false'
+BreakBeforeBraces: 'Linux'
+ColumnLimit: '100'
+DerivePointerAlignment: 'false'
+IndentCaseLabels: 'false'
+IndentWidth: '8'
+KeepEmptyLinesAtTheStartOfBlocks: 'false'
+Language: 'Cpp'
+MaxEmptyLinesToKeep: '1'
+PointerAlignment: 'Right'
+SortIncludes: 'false'
+SpaceAfterCStyleCast: 'false'
+SpaceBeforeAssignmentOperators : 'true'
+SpaceBeforeParens: 'ControlStatements'
+SpaceInEmptyParentheses: 'false'
+SpacesInSquareBrackets: 'false'
+TabWidth: '8'
+UseTab: 'AlignWithSpaces'
+PenaltyBreakAssignment: '3'
+PenaltyBreakBeforeFirstCallParameter: '15'
+
+# Local Variables:
+# mode: yaml
+# End:

.editorconfig

@@ -2,6 +2,7 @@
 # editorconfig file (see EditorConfig.org), with some
 # lowest-denominator settings that should work for many editors.
 
+
 root                        = true # this is the top-level
 
 [*]
@@ -10,23 +11,20 @@ insert_final_newline        = true
 charset                     = utf-8
 trim_trailing_whitespace    = true
 
-# The "best" answer is "tabs-for-indentation; spaces for alignment", but in
+# The "best" answer is "tabs-for-indentation; spaces for alignment".
-# practice that's hard to accomplish in many editors.
-#
-# So we use spaces instead, at least that looks consistent for all
 
 [*.{cc,cpp,hh,hpp}]
-indent_style                = space
+indent_style                = tab
 indent_size                 = 8
 max_line_length             = 100
 
 [*.{c,h}]
-indent_style                = space
+indent_style                = tab
 indent_size                 = 8
 max_line_length             = 80
 
 [configure.ac]
-indent_style                = space
+indent_style                = tab
 indent_size                 = 4
 max_line_length             = 100