Fix build error for IntelliJ after fake sourceSet htroot has been add ( dfc7a23e60 )

commit dfc7a23e60  uncomments the fake additional Gradle sourceSet (to make htroot in IDE visible), resulting in build error in IntelliJ IDEA if one uses just the IDE build button (and the old Ant build.xml is not available ... what is to expect soon).
This button runs as to expect the default Gradle task
   > Task :htrootClasses    (not our task compileHtrootServlets)
result :
htroot\processing\domaingraph\applet\domaingraph.java:1: error: package processing.core does not exist
import processing.core.*; import traer.physics.*; import traer.animation.*; import processing.net.*; import java.applet.*; import java.awt.*; import java.awt.image.*; import java.awt.event.*; import java.io.*; import java.net.*; import java.text.*; import java.util.*; import java.util.zip.*; public class domaingraph extends PApplet {// Domain visualization graph for YaCy

.idea/ant.xml

@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="AntConfiguration">
-    <buildFile url="file://$PROJECT_DIR$/build.xml" />
-  </component>
-</project>

README.md

@@ -145,7 +145,7 @@ adjust it [Here](http://localhost:8090/ConfigHTCache_p.html) to fit your needs.
 Join the large number of contributors that make YaCy what it is;
 community software.
 
-To start developing YaCy in Eclipse:
+To start developing YaCy in [Eclipse:](https://www.eclipse.org/)
 
 - Clone https://github.com/yacy/yacy_search_server.git
 - File → Import as Git → Projects from Git → Existing local repository
@@ -155,14 +155,14 @@ To start developing YaCy in Eclipse:
 - → Name: "YaCy Build" → Buildfile: Browse Workspace → build.xml → Run
 - In the Package Explorer, right-click on YaCy → Run as → Java Application -> Select "yacy - net.yacy" -> OK
 
-To start developing YaCy in Netbeans:
+To start developing YaCy in [Netbeans:](https://netbeans.apache.org/)
 
 - clone https://github.com/yacy/yacy_search_server.git (Team → Git → Clone)
     - if you checked "scan for project" you'll be ask to open the project
 - Open the project (File → Open Project)
 - you may directly use all the Netbeans build feature.
 
-To start developing YaCy in IntelliJ IDEA
+To start developing YaCy in [IntelliJ IDEA:](https://www.jetbrains.com/idea/)
 
 - clone https://github.com/yacy/yacy_search_server.git
 - File -> New -> Project from Version Control -> URL (see above) -> Clone

build.gradle

@@ -36,7 +36,8 @@ sourceSets {
 
     htroot { // optional sourceset to have htroot servelets available/visible in development IDE
         java {
-	        srcDirs = ['htroot']
+	    srcDirs = ['htroot']
+            exclude 'processing/**'
             compileClasspath = configurations.compileClasspath + jar.outputs.files
         }
     }