[MetaCRS] Equirectangular / Equidistant Cylindrical Parameters

[Martin Desruisseaux]

Hello Frank

If I'm understanding right, the "Latitude of natural origin" in Mercator_1SP
(EPSG:9804) serves the same purpose; it is the latitude where the scale is close
to true. And nevertheless it is called "Latitude of natural origin".

(Just for checking, I compared the part of Mercator formulas that applies to x
ordinates with the Equirectangular formulas in the Ellipsoidal case, using Earth
radius R = sqrt((a^2 * (1 – e^2)) / (1 – e^2 sin^2 latO)^2) as described in EPSG
documentation for EPSG:9823. I found the same result except for a constant
factor of sqrt(1 - e^2), which is close to 1).

EPSG is updated more often than Synder, and I have the feeling that they try to
comply to common usage. For example they changed the spelling of "Molodenski" to
"Molodensky" in August 2004 for that reason.

	Martin