Fix issue#8, fold data into different rows when its size is more than MAX_TEXTURE_SIZE

[JackieAnxis]

For the graph example, when visualizing a graph with more than MAX_TEXTURE_SIZE (it may be 2^14 or 2^15), webGL will report that: WebGL: INVALID_VALUE: texImage2D: width or height out of range.
Now, the data is bound to texture with one row (newData.width = data.length; newData.height = 1), when the length of data exceeds the MAX_TEXTURE_SIZE, it will not be visualized.
I fold the data into several rows in the texture (newData.width = data.length > MAX_TEXTURE_SIZE ? MAX_TEXTURE_SIZE : data.length; newData.height = Math.ceil(data.length / MAX_TEXTURE_SIZE)), so that its length will not exceed the MAX_TEXTURE_SIZE.

[JackieAnxis]

For the graph example, when visualizing a graph with more than MAX_TEXTURE_SIZE (it may be 2^14 or 2^15), webGL will report that: WebGL: INVALID_VALUE: texImage2D: width or height out of range. Now, the data is bound to texture with one row (newData.width = data.length; newData.height = 1), when the length of data exceeds the MAX_TEXTURE_SIZE, it will not be visualized. I fold the data into several rows in the texture (newData.width = data.length > MAX_TEXTURE_SIZE ? MAX_TEXTURE_SIZE : data.length; newData.height = Math.ceil(data.length / MAX_TEXTURE_SIZE)), so that its length will not exceed the MAX_TEXTURE_SIZE.

This PR will fix #8