resolve issue #1926 (unnecessary dependencies) (#1927)

* buildscript: move def of "niftyVersion" to "common.gradle" (shared between projects)

* jme3-testdata:  rm dependency on "nifty-style-black" (redundant with "jme3-niftygui")

* buildscript: mv "nifty-examples" dependency from "jme3-testdata" to "jme3-examples"

common.gradle

@@ -27,6 +27,7 @@ tasks.withType(JavaCompile) { // compile-time options:
 
 ext {
     lwjgl3Version = '3.3.1' // used in both the jme3-lwjgl3 and jme3-vr build scripts
+    niftyVersion = '1.4.3' // used in both the jme3-niftygui and jme3-examples build scripts
 }
 
 repositories {

jme3-examples/build.gradle

@@ -27,6 +27,7 @@ dependencies {
     implementation project(':jme3-terrain')
     implementation project(':jme3-awt-dialogs')
     runtimeOnly project(':jme3-testdata')
+    runtimeOnly "com.github.nifty-gui:nifty-examples:${niftyVersion}" // for the "all/intro.xml" example GUI
 }
 
 jar.doFirst{

jme3-niftygui/build.gradle

@@ -1,5 +1,3 @@
-def niftyVersion = '1.4.3'
-
 dependencies {
     api project(':jme3-core')
     api "com.github.nifty-gui:nifty:${niftyVersion}"

jme3-testdata/build.gradle

@@ -1,6 +1,2 @@
-def niftyVersion = '1.4.3'
-
 dependencies {
-    runtimeOnly "com.github.nifty-gui:nifty-examples:$niftyVersion"
-    runtimeOnly "com.github.nifty-gui:nifty-style-black:$niftyVersion"
 }