Distribution-specific files: remove from repo & add to .gitignore

[sadielbartholomew]

Some distribution-related files have been committed previously to the top level of the repository, but these aren't useful for anything and could quite actively confuse package managers if the repo is cloned. At present they just bloat the repo, so should be removed. These are:

• the whole cf_plot.egg-info directory;
• the MANIFEST file, but not the MANIFEST.in file which is important to identify what gets included in the distribution.

[sadielbartholomew]

Ah I meant to open this on the cf-plot Issue Tracker, naturally. Let me try to transfer via the settings...