Update the project to Android Studio 3.3 and Gradle 4.10.1 (#221)

- Updated Gradle to version 4.10.1
- Updated the Android Gradle plugin to version 3.3.2
- Updated the Travis CI configuration to build with Androig Gradle plugin 3.3.2
- Updated gradle.properties to use the new Android Studio defaults
- Applied changes to the IntelliJ IDEA project configuration files
- Corrected a warning in GmlRectifiedGrid.java

Author: David Collins

.gitignore

@@ -2,6 +2,8 @@
 
 .gradle
 
+.idea/caches
+
 .idea/libraries
 
 .idea/misc.xml