Refactored tools structure & conventions for reuse (#685)

1.  All common tools are hosted and managed in
    the tools directory (used for both local development
    and continuous integration)
2.  Each tool comprises a directory, akin to a bundle,
    that encapsulates declarative command-line options,
    configuration files and a run script
3.  A single bootstrap script configures a
    development environment
4.  A lightweight runtime provides a common set of
    convenience functions and variables to all scripts

References #672

.tools/cppcheck/run.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+# Instantiate the tool runtime shim
+. "$(git mystoolspath).bundle_runtime.sh"
+
+# cppcheck takes one or more files as an argument.
+# --cached or <no arg> for changed
+if [[ $# = 0 ]]; then
+	for file in $(modifiedSourceFiles); do
+		runBundle $file
+	done
+elif [[ $1 = '--cached' ]]; then
+	for file in $(stagedSourceFiles); do
+		runBundle $file
+	done
+else
+	eval "set -- $(git rev-parse --sq --prefix "$GIT_PREFIX" "$@")"
+	runBundle "$@"
+fi