Add min_value and max_value C++ formatting.

Also changed formatting of scalar float 0 and 1 and zero to 0.0, 1.0.
Add edge vectors types.
Fix access to cell edge vectors.
minor fix
Fix cell entity access. Make num_points available in backend access
to support multiple integration rules (not tested).
Minor renames.
whitespace fix
Run autopep8 E1* whitespace fixes.
Run autopep8 E2* whitespace fixes.
Run autopep8 E3* whitespace (newline) fixes.
Run autopep8 E7* fixes.
whitespace fix
Add explicit imports to ffc backend files.
Remove unused imports.
Remove more unused imports.
Remove even more unused imports.
Remove imports in codeutils.
remove imports in generaiton.
Remove unused imports from analysis.
Fix imports with pylint.
Fix various pylint reported issues.