initial hdf5 save code
Implement rest of hdf5 file saving
cleanup of main window to separate loading python code
Merge branch 'master' into save-hdf

Conflicts:
	veusz/document/datasets.py
Fix broken merge
Catch unicode decoding error in Veusz file. Do not duplicate documentsetup.
Move code for executing scripts out of the main window into its own function.

Uses callback to report security issues.
Use translatable strings for command interface
Store all data types in groups
Added code to read HDF5 files
Implement saving hdf5 files from save dialog. Remember chosen filetype.
Do not show hdf5 save format if h5py missing
Do not show vszh5 files for loading if no h5py
Fix self tests when resaving test as hdf5 and reloading
Create a base 1d dataset type to prevent evaluations of datasets before usage.
Make editable a property of dataset, rather than method.
Add self test options for testing resaving examples
Disable doc updates while loading hdf5 documents
Fix 1dto2d test when resaving
Decode text from HDF5 files
ur"" strings cannot be used in Py3, therefore saved text datasets
cannot be used.

Instead use SetDataText() and use a list of repr'd strings
when saving files.