Chunked tables: create new chunk when all existing ones are too big

[answerquest]

When provisioning new data like new shapes or trips, typically a smallestChunk function finds the smallest .h5 file to put the new data in.

Set an absolute max file size, and if all the chunks have become bigger than this limit, then provision a new chunk.

[answerquest]

Added some steps in smallestChunk function:

    sizeList = [ os.path.getsize(os.path.join(dbFolder, filename))/(2**20) for filename in filenames ]
    # get sizes in MB
    if min(sizeList) < maxSizeMB:
        chunkFile = filenames[ sizeList.index(min(sizeList)) ]

    else:
        nextChunkNum = len(filenames) + 1
        chunkFile = '{}_{}.h5'.format(prefix, nextChunkNum)
        logmessage('smallestChunk: All chunks for {} too big, lets create a new one, {}'.format(prefix,chunkFile))
    return chunkFile

[answerquest]

already fixed with v3.1.0