Tweak to setup and version bump to allow PyPI upload pyslha-1.4.3

Added tag pyslha-1.4.2 for changeset c04a4be80445 Adding install_requires for tex2pix so that PyPI/easy_install/pip automatic dependency handling will work. Version 1.4.2 pyslha-1.4.2

Adding a naive --aspect-ratio option, but the output is not ideal.

Added tag pyslha-1.4.1 for changeset 72b624585d14

Oops, missed version update pyslha-1.4.1

Added tag pyslha-1.4.1 for changeset b4524d505120

Adding the --include command line option, which allows user-customisable additions to the plot.

Notes about TODOs

Added tag pyslha-1.4.0 for changeset 3bab09178112

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