Use setuptools entry_points console_scripts to install command line tools

This provides a more consistent experience across platforms. It allows the ".py" extension to be omitted from the command line tools, and setuptools ensures the correct python interpreter is called and makes sure everything works on Windows as well.

The scripts are now just automatically generated by referring to a function in the package, so dumppdf.py, pdf2txt.py and latin2ascii.py have just been moved into the main pdfminer package. It might be worth considering something like a "cli" sub-package, especially if the number of command line tools grows.
Optimizations by brechin https://github.com/brechin/pdfminer2/commit/b2a41e64b9a65c8a0d7d565af5244f3edd293aba

Moved the dist and isany functions to utils, and use a different method for calculating the overall bounding box around two objects (now in tb_bound).