[plot gl] is there a size limit for plotting RGB images with the gl backend?
I'm trying to show RGB images with the silx plot using the gl backend, and I get an error for large files only (~900Mb). It works ok with smaller images (~500 Mb).

With the backend mpl, I was able to display (slowly) all of these images.

To replicate :
```
from silx.gui import qt
from silx.gui.plot import Plot2D
import numpy
# from PIL import Image
# Image.MAX_IMAGE_PIXELS = None

app = qt.QApplication([])
plt = Plot2D(backend="gl")

img = numpy.arange(22386*15182*3, dtype=numpy.uint8)
img.shape = (22386, 15182, 3)

plt.addImage(img)
plt.show()

app.exec_()
```

And the error is:
```
Traceback (most recent call last):
  File "/home/pierre/.local/lib/python3.7/site-packages/silx/gui/_glutils/OpenGLWidget.py", line 234, in paintGL
    parent.paintGL()
  File "/home/pierre/.local/lib/python3.7/site-packages/silx/gui/plot/backends/BackendOpenGL.py", line 548, in paintGL
    self._paintFBOGL()
  File "/home/pierre/.local/lib/python3.7/site-packages/silx/gui/plot/backends/BackendOpenGL.py", line 492, in _paintFBOGL
    self._renderPlotAreaGL()
  File "/home/pierre/.local/lib/python3.7/site-packages/silx/gui/plot/backends/BackendOpenGL.py", line 742, in _renderPlotAreaGL
    isXLog, isYLog)
  File "/home/pierre/.local/lib/python3.7/site-packages/silx/gui/plot/backends/glutils/GLPlotImage.py", line 674, in render
    self._renderLinear(matrix)
  File "/home/pierre/.local/lib/python3.7/site-packages/silx/gui/plot/backends/glutils/GLPlotImage.py", line 599, in _renderLinear
    self.prepare()
  File "/home/pierre/.local/lib/python3.7/site-packages/silx/gui/plot/backends/glutils/GLPlotImage.py", line 590, in prepare
    texUnit=self._DATA_TEX_UNIT)
  File "/home/pierre/.local/lib/python3.7/site-packages/silx/gui/plot/backends/glutils/GLTexture.py", line 170, in __init__
    wrap=self._WRAP)
  File "/home/pierre/.local/lib/python3.7/site-packages/silx/gui/_glutils/Texture.py", line 73, in __init__
    assert shape is None
AssertionError
```

```
pip3 list 
PyOpenGL                      3.1.0 
PySide2                       5.12.3  
silx                          0.10.1 
numpy                         1.16.3   
```

diff --git a/silx/gui/plot/backends/glutils/GLTexture.py b/silx/gui/plot/backends/glutils/GLTexture.py
index 25dd9f154..118a36f4b 100644
--- a/silx/gui/plot/backends/glutils/GLTexture.py
+++ b/silx/gui/plot/backends/glutils/GLTexture.py
@@ -1,7 +1,7 @@
 # coding: utf-8
 # /*##########################################################################
 #
-# Copyright (c) 2014-2017 European Synchrotron Radiation Facility
+# Copyright (c) 2014-2019 European Synchrotron Radiation Facility
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to deal
@@ -163,7 +163,6 @@ class Image(object):
                                           data[yOrig:yOrig+hData,
                                                xOrig:xOrig+wData],
                                           format_,
-                                          shape=(hData, wData),
                                           texUnit=texUnit,
                                           minFilter=self._MIN_FILTER,
                                           magFilter=self._MAG_FILTER,
['silx/gui/plot/backends/glutils/GLTexture.py']