relax checkstyle, add comments to grammar

fix #1
3 jobs for master in 1 minute and 59 seconds
Status Job ID Name Coverage
  Test
passed #12882
build

00:00:25

passed #12884
deploy

00:01:03

failed #12883
test

00:00:30

 
Name Stage Failure
failed
test Test There is an unknown failure, please try again
[ERROR] Please refer to /builds/xt9634/ProofScriptParser/target/surefire-reports for the individual test results.
[ERROR] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException
ERROR: Job failed: exit code 1