Remove redundant NULL checks.
mrb_malloc causes an exception when memory was empty.
Add tests for mruby-eval.
Don't use ensure to fix crash of mruby-eval test.
Merge pull request #1948 from monaka/pr-remove-unused-null-check

Remove redundant NULL checks.
should not over process ensure clauses; close #1949
Merge branch 'eval_test' of https://github.com/take-cheeze/mruby into take-cheeze-eval_test
revert 813ba5 since #1949 fixed
Catch up to latest Arduino IDE
Merge pull request #1952 from kyab/catchup_arduinodue

Catch up to latest Arduino IDE
Merge remote-tracking branch 'upstream/master' into ext