[BREAKING] Hermert: add +convention=position_vector/coordinate_frame, forbids +transpose (fixes #1091)

As identified in #1091, Helmert implementation in PROJ 5.0 and 5.1 is confusing.
It happens that by default it used the coordinate_frame convention, contrary to
the position_vector convention used traditionaly for +towgs84. The documentation
of Helmert was also wrongly specifying that the default convention was
position_vector.

This commit:
- bans the confusing +transpose parameter
- removes the concept of a default convention, since in practice both are
  equally found, and requires +convention as soon as a rotational term parameter
  is present.
  For translation only, convention is ignored and optional, as having no effect.
- fixes all the identified uses of proj=helmert in code, doc and tests

This is obviously a breaking change:
- users will have to adapt their pipeline expressions
- in particular, init files that would use helmert must be adapted

However, as designed, the break will be explicit, and not silent.

1 files changed, 10 insertions, 10 deletions

diff --git a/nad/ITRF2000 b/nad/ITRF2000
index f0a80db6..a7064f3b 100644
--- a/nad/ITRF2000
+++ b/nad/ITRF2000
@@ -3,22 +3,22 @@
 
 # ITRF2000 -> ITRF2005 is only defined the opposite way, so we flip the sign on all
 # parameters to get the opposite transformation. Parameters from http://itrf.ign.fr/ITRF_solutions/2005/tp_05-00.php
-<ITRF2005> +proj=helmert +x=-0.0001 +y=0.0008 +z=0.0058 +s=-0.0004 +dx=0.0002 +dy=-0.0001 +dz=0.0018 +ds=-0.000008 +t_epoch=2000.0 +transpose
+<ITRF2005> +proj=helmert +x=-0.0001 +y=0.0008 +z=0.0058 +s=-0.0004 +dx=0.0002 +dy=-0.0001 +dz=0.0018 +ds=-0.000008 +t_epoch=2000.0 +convention=position_vector
 
-<ITRF97> +proj=helmert +x=0.0067 +y=0.0061 +z=-0.0185 +s=0.00155 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1997.0 +transpose
+<ITRF97> +proj=helmert +x=0.0067 +y=0.0061 +z=-0.0185 +s=0.00155 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1997.0 +convention=position_vector
 
-<ITRF96> +proj=helmert +x=0.0067 +y=0.0061 +z=-0.0185 +s=0.00155 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1997.0 +transpose
+<ITRF96> +proj=helmert +x=0.0067 +y=0.0061 +z=-0.0185 +s=0.00155 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1997.0 +convention=position_vector
 
-<ITRF94> +proj=helmert +x=0.0067 +y=0.0061 +z=-0.0185 +s=0.00155 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1997.0 +transpose
+<ITRF94> +proj=helmert +x=0.0067 +y=0.0061 +z=-0.0185 +s=0.00155 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1997.0 +convention=position_vector
 
-<ITRF93> +proj=helmert +x=0.0127 +y=0.0065 +z=-0.0209 +s=0.00195 +rx=-0.00039 +ry=0.00080 +rz=-0.00114 +dx=-0.0029 +dy=-0.0002 +dz=-0.0006 +ds=0.00001 +drx=-0.00011 +dry=-0.00019 +drz=0.00007 +t_epoch=1988.0 +transpose
+<ITRF93> +proj=helmert +x=0.0127 +y=0.0065 +z=-0.0209 +s=0.00195 +rx=-0.00039 +ry=0.00080 +rz=-0.00114 +dx=-0.0029 +dy=-0.0002 +dz=-0.0006 +ds=0.00001 +drx=-0.00011 +dry=-0.00019 +drz=0.00007 +t_epoch=1988.0 +convention=position_vector
 
-<ITRF92> +proj=helmert +x=0.0147 +y=0.0135 +z=-0.0139 +s=0.00075 +rz=-0.00018 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1988.0 +transpose
+<ITRF92> +proj=helmert +x=0.0147 +y=0.0135 +z=-0.0139 +s=0.00075 +rz=-0.00018 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1988.0 +convention=position_vector
 
-<ITRF91> +proj=helmert +x=0.0267 +y=0.0275 +z=-0.0199 +s=0.00215 +rz=-0.00018 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1988.0 +transpose
+<ITRF91> +proj=helmert +x=0.0267 +y=0.0275 +z=-0.0199 +s=0.00215 +rz=-0.00018 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1988.0 +convention=position_vector
 
-<ITRF90> +proj=helmert +x=0.0247 +y=0.0235 +z=-0.0359 +s=0.00245 +rz=-0.00018 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1988.0 +transpose
+<ITRF90> +proj=helmert +x=0.0247 +y=0.0235 +z=-0.0359 +s=0.00245 +rz=-0.00018 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1988.0 +convention=position_vector
 
-<ITRF89> +proj=helmert +x=0.0297 +y=0.0475 +z=-0.0739 +s=0.00585 +rz=-0.00018 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1988.0 +transpose
+<ITRF89> +proj=helmert +x=0.0297 +y=0.0475 +z=-0.0739 +s=0.00585 +rz=-0.00018 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1988.0 +convention=position_vector
 
-<ITRF88> +proj=helmert +x=0.0247 +y=0.0115 +z=-0.0979 +s=0.00895 +rx=0.0001 +rz=-0.00018 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1988.0 +transpose
+<ITRF88> +proj=helmert +x=0.0247 +y=0.0115 +z=-0.0979 +s=0.00895 +rx=0.0001 +rz=-0.00018 +dy=-0.0006 +dz=-0.0014 +ds=0.00001 +drz=0.00002 +t_epoch=1988.0 +convention=position_vector