Make CLANG_TIDY non-pendantic

First, we have to fix numerous warnings.

Author: rhaschke

.clang-tidy

@@ -1,6 +1,5 @@
 ---
-Checks:          '-*,
-                  llvm-namespace-comment,
+Checks:          'llvm-namespace-comment,
                   modernize-redundant-void-arg,
                   modernize-use-nullptr,
                   modernize-use-default,

.github/workflows/ci.yaml

@@ -16,7 +16,7 @@ jobs:
         include:
           - distro: melodic
             env:
-              CLANG_TIDY: pedantic
+              CLANG_TIDY: true
 
     env:
       CXXFLAGS: "-Werror -Wall -Wextra -Wwrite-strings -Wunreachable-code -Wpointer-arith -Wredundant-decls -Wno-strict-aliasing -Wno-sign-compare"