Fixed issue #4902.

Extended _ensure_numeric to check if the value is a complex numbers.
Also it now tries to convert the value to a complex number if conversion to float fails.
Added PyDev project files to .gitignore.
Merge branch 'iss4902' of https://github.com/alefnula/pandas into alefnula-iss4902

Conflicts:
	doc/source/release.rst
CLN: more plotting test cleanups
Merge pull request #4912 from cpcloud/plotting-test-cleanup

CLN: more plotting test cleanups
ENH: Add 'is_' method to Index for identity checks

Adds a method that can quickly tell whether something is a view or not
(in the way that actually matters).

Test cases and basic setup for is_ method

CLN: change 'is' check to 'is_' check in 'equals()'
Change _Identity to just be an alias for object, instead of a separate class