fullScreen.xml: remove image generation tags

causing Travis-CI buld to fail with:

> 3 failure(s)
> The command "./generator.py build --all --images" exited with 1.

From the log:

```
Image process ... RUNNING: fullScreen2
Image process ... DEBUG: NullPointerException - fullScreen2 is probably dynamic-mode; fix that, please.
Image process ... FAILURE: fullScreen2
Image process ... RUNNING: fullScreen3
Image process ... DEBUG: NullPointerException - fullScreen3 is probably dynamic-mode; fix that, please.
Image process ... FAILURE: fullScreen3
Image process ... RUNNING: fullScreen1
Image process ... DEBUG: NullPointerException - fullScreen1 is probably dynamic-mode; fix that, please.
Image process ... FAILURE: fullScreen1

...

Failed examples:
     fullScreen2
     fullScreen3
     fullScreen1
```

Author: jeremydouglass

Reference/api_en/fullScreen.xml

@@ -9,7 +9,6 @@
 <type></type>
 
 <example>
-<image></image>
 <notest/>
 <code><![CDATA[
 # Run the code at the full dimensions of the screen currently
@@ -31,7 +30,6 @@ def draw():
 </example>
 
 <example>
-<image></image>
 <code><![CDATA[
 # If more than one screen is attached to the computer, run the 
 # code at the full dimensions on the screen defined by the 
@@ -53,7 +51,6 @@ def draw():
 </example>
 
 <example>
-<image></image>
 <code><![CDATA[
 # Run full screen using the P2D renderer on screen 2
 
@@ -73,7 +70,6 @@ def draw():
 </example>
 
 <example>
-<image></image>
 <code><![CDATA[
 # If more than one screen is attached to the computer, run the 
 # code at the full dimensions across all of the attached screens