Rename proj_create() to proj_trans_create()

[anthonynorth]

Renamed proj_create() to proj_trans_create().

[anthonynorth]

@mdsumner I've not preserved the proj_create() name. Given it was only added to the package namespace a few weeks ago and between CRAN releases, I thought it not necessary to do.

[mdsumner]

yes fwiw consider main branch as totally unstable, I'm happy to go all out atm - we can rename and fix after discussions if needed, just get the functionality in, no need to worry about backwards compat for stuff not on cran 🙏 you have commit access too, if you want to use that