[Mac] Unable to build with Maven

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### Environment
**OS:** macOS Mojave
**Python:** Python 3.7.2 / virtualenv
**JDK:** JDK8 update201
**SikuliLibrary:** Latest source code from GitHub, built with maven on macOS Mojave, run setup.py to install

### Description
Unable to build with Maven, log:

```
[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR] /Users/hideman/Downloads/robotframework-SikuliLibrary-master/src/java/com/github/rainmanwy/robotframework/sikulilib/keywords/ApplicationKeywords.java:[27,25] incompatible types: boolean cannot be converted to org.sikuli.script.App
[INFO] 1 error
[INFO] -------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 4.138 s
[INFO] Finished at: 2019-01-26T02:12:36+08:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project robotframework-SikuliLibrary: Compilation failure
[ERROR] /Users/hideman/Downloads/robotframework-SikuliLibrary-master/src/java/com/github/rainmanwy/robotframework/sikulilib/keywords/ApplicationKeywords.java:[27,25] incompatible types: boolean cannot be converted to org.sikuli.script.App
[ERROR]
[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

```

Start by running the Maven build with the reported macOS, JDK 8, and Python environment, then inspect src/java/com/github/rainmanwy/robotframework/sikulilib/keywords/ApplicationKeywords.java at line 27. Trace the incompatible boolean and org.sikuli.script.App types through the relevant dependency usage. Done means the project compiles successfully with Maven.

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