Replace every EXV_ symbol with EXIV2_

[clanmills]

I've never understood the advantage in removing vowels from symbol names. It's a relic of UNIX in 1968 or something. It's difficult to type and makes no sense.

Doing this has an enormous ripple through the code base. Much too brutal to be applied to a release candidate. It'll be done on 'main' early in the v1.00 project.

The only relic of this that should endure is the .exv file format which is supported by ExifTool.

[kmilos]

Yeah, it looks like there is no real need to duplicate EXIV2_* cmake options with new EXV_* variables that are used in cmake/config.h.cmake, one could use directly the EXIV2_* options in that header template instead; see the example at the bottom here.

[paolobenve]

is this issue only matter of replacing every EXV_ prefix with EXIV2_?

[kmilos]

Not only, some cleanup of CMake related files is also needed...

[clanmills]

@kmilos: Lots of very good work was done on the CMake code by @piponazo. Be sure to ask him to review any changes you make.

@paolobenve: It's more or less what you've said. I always expect something unexpected! https://www.youtube.com/watch?v=Cj8n4MfhjUc