Require Java 8 (1.8)

Signed-off-by: David Smiley <[email protected]>

Author: dsmiley

README.md

@@ -51,7 +51,7 @@ For more information on the formats supported, see [FORMATS.md](FORMATS.md).
 
 ## Dependencies
 
-Spatial4j runs on Java -- version 1.7 or better, though is only really tested on 1.8.  Otherwise, all dependencies listed in the maven [pom.xml](pom.xml) are either marked optional or are for testing. The optional dependencies are:
+Spatial4j runs on Java 8 (v1.8) or better.  Otherwise, all dependencies listed in the maven [pom.xml](pom.xml) are either marked optional or are for testing. The optional dependencies are:
 * [JTS](https://github.com/locationtech/jts):  You need JTS if you use polygons, or obviously if you use any of the classes prefixed with "Jts".
 * [Noggit](https://github.com/yonik/noggit): The Noggit JSON parsing library is only needed for GeoJSON parsing (not required for writing).
 * [Jackson-databind](https://github.com/FasterXML/jackson-databind): If you wish to use Spatial4j's Jackson-databind feature to read/write shapes.

pom.xml

@@ -90,6 +90,8 @@
   <properties>
     <!-- this magic system property is honored by many plugins: http://docs.codehaus.org/display/MAVENUSER/POM+Element+for+Source+File+Encoding -->
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <maven.compiler.source>1.8</maven.compiler.source>
+    <maven.compiler.target>1.8</maven.compiler.target>
   </properties>
 
   <!-- To check for new plugins and dependencies:
@@ -197,8 +199,6 @@
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>
         <configuration>
-          <source>1.7</source>
-          <target>1.7</target>
           <optimize>true</optimize>
           <showDeprecation>true</showDeprecation>
         </configuration>
@@ -233,7 +233,6 @@
             The checker simply passes by default and only prints a warning.
            -->
           <failOnUnsupportedJava>false</failOnUnsupportedJava>
-          <targetVersion>1.7</targetVersion>
         </configuration>
       </plugin>
 
@@ -344,7 +343,6 @@
         <configuration>
           <linkXRef>true</linkXRef>
           <minimumTokens>100</minimumTokens>
-          <targetJdk>1.7</targetJdk>
         </configuration>
       </plugin>