Add clang-tidy, create Linux build script

clang-tidy is currently set up with errors for all checks that do not
warn. This is to prevent regressing the repo.

Gradually these warnings should be removed in order to prevent further
regresssions in warnings that do not have many occurences.

build_scripts/linux/build_linux.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+set -e
+if [[ -z $QMAKE_SPEC ]]; then
+    QMAKE_SPEC='linux-g++'
+fi
+
+if [[ -z $USE_TIDY ]]; then
+    MAKE_COMMAND='make --jobs'
+    CLANG_TIDY=
+else
+    # Bear replaces the compile database, it does not update it.
+    # If you run 'bear make' and there is nothing to compile, you
+    # will get an empty database.
+    # Clean up the artifacts and run everything together in that case.
+    MAKE_COMMAND='bear make --jobs'
+    QMAKE_SPEC='linux-clang'
+    CLANG_TIDY='../build_scripts/linux/run-clang-tidy.sh'
+fi
+
+echo $MAKE_COMMAND
+mkdir -p build
+cd build
+qmake --version
+qmake -spec $QMAKE_SPEC ..
+$MAKE_COMMAND
+$CLANG_TIDY