BUG: inconsistent and undocumented option "converters" to read_excel
Issue #8212 (first part): pandas.read_excel accepts an optional argument "converters"  (which is passed down to PythonParser) to convert single cells in columns with a conversion function. I documented this feature and added a try/except block to make it work in case some cells contain NaNs.

What's still missing is the full "dtype" argument, a la read_csv. That patch is somewhat orthogonal because it only works with the C parser, so I plan to implement it in a second step.

usually start off a PR with tests first.
 I added a test for this functionality.
 ok, this looks fine
- need a release note in v0.15.0 (refere the issue you highlited above). as you are now allowing the converters argument to work with missing values. maybe adjust the docs a bit in doc/source/io.rst (excel section).
 I added some docs there, not sure it's enough, open for feedback.
 Hi, what's the current status on this? I think I implemented all you requested, do you think it's ready and can be merged?
No pressure, I am just trying to join loose ends...
 ok, pls edit the docs a bit, rebase and squash.
 Ok, edited docs, squashed, rebased, pushed (d0597b8).
 looks ok to me

@jorisvandenbossche ?
 Thanks!
 Thanks! I'm happy since it's my first PR and I made a bit of a mess. I'll try to work on the full dtype integration, using the C parser.
