Rename ol.projection.getFromCode to ol.projection.get
Allow strings to be used wherever projections are needed
Use strings rather than ol.projection.get in examples
Rename projection functions for a friendlier API

The following functions are renamed:

getTransform -> getTransformForProjections
getTransformFromCodes -> getTransform
transform -> transformWithProjections
transformWithCodes -> transform

With this change, the faster functions that avoid projection look-up
have longer names and are used internally, whereas the slower but
friendlier short name functions are available for users.
Merge pull request #272 from twpayne/projection-get

allow people to specify projection as a string