[ACID]Fix testcase 114 imageOrientation_inline

Inlining images in TikZ code is fixed by replacing `length` with `numel`. The error is caused by creating an image with `image(magic(3))`, since then `cData` has the dimensions `3x3`.

The change below tries to identify a RGB triplet. Thus `numel` should be used to check the size of `cData`.

R2014b:
![acid_imageorientation_r2014b_inline](https://cloud.githubusercontent.com/assets/4340267/4918834/e4a0a0f4-64f4-11e4-964e-d137ca7d56f2.png)