Ignore generated documentation.

Check for invalid opacity values.

.gitignore

@@ -56,6 +56,7 @@ Thumbs.db
 *.dylib
 *.dll
 /scratch/
+/documentation/
 
 # Eclipse
 .classpath

core/src/test/java/documentation/CreateUITable.java

@@ -280,6 +280,7 @@ public class CreateUITable {
             for (Object child : children) {
                 if (child instanceof LinearGradient) {
                     float opacity = IconColorMapper.getOpacity((LinearGradient) child, currentDefaults);
+                    if (opacity < 0) opacity = 1;
                     Color color = IconColorMapper.getColor((LinearGradient) child, currentDefaults);
                     String id = ((LinearGradient) child).getId();
                     String match = "=\"url\\(#" + id + "\\)\"";