CI check generate code (#4998)

* call reflection code generation from tests

This simplifies instructions to contributors so they don't forget to update
reflection code.

* add error handling to generate_code scripts

Let them propagate their errors instead of swallowing them so they show
up when called in CI.

* apply editorconfig to shell scripts

* use ordered map in dart codegen

Using an unordered map in the codegen can lead to spurious diffs in the
generated dart code.

* add CI check for generate_code being run

* update reflection_generated.h

* disable diff-check for monster_test.bfbs

Work around #5008.

.appveyor/check-generate-code.bat

@@ -0,0 +1,40 @@
+:: Copyright 2018 Google Inc. All rights reserved.
+::
+:: Licensed under the Apache License, Version 2.0 (the "License");
+:: you may not use this file except in compliance with the License.
+:: You may obtain a copy of the License at
+::
+::     http://www.apache.org/licenses/LICENSE-2.0
+::
+:: Unless required by applicable law or agreed to in writing, software
+:: distributed under the License is distributed on an "AS IS" BASIS,
+:: WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+:: See the License for the specific language governing permissions and
+:: limitations under the License.
+set buildtype=Release
+if "%1"=="-b" set buildtype=%2
+
+cd tests
+call generate_code.bat -b %buildtype% || goto FAIL
+
+:: TODO: Release and Debug builds produce differences here for some reason.
+git checkout HEAD -- monster_test.bfbs
+
+git -c core.autocrlf=true diff --exit-code --quiet || goto :DIFFFOUND
+goto SUCCESS
+
+:DIFFFOUND
+@echo "" >&2
+@echo "ERROR: ********************************************************" >&2
+@echo "ERROR: The following differences were found after running the" >&2
+@echo "ERROR: tests/generate_code.sh script.  Maybe you forgot to run" >&2
+@echo "ERROR: it after making changes in a generator or schema?" >&2
+@echo "ERROR: ********************************************************" >&2
+@echo "" >&2
+@git -c core.autocrlf=true --no-pager diff --binary
+
+:FAIL
+set EXITCODE=1
+:SUCCESS
+cd ..
+EXIT /B %EXITCODE%