[Esteban82]

Description of proposed changes
Two settings that are read per event in meca (and coupe) leaked into the events that follow:

• -A (coupe -D): if an event gives an alternate location (newX newY), or offsets dx dy with +o, the next events that give none are moved to that same place (or by the same offset). In the image the second event is drawn on top of the first one.
• -I with intensities read from the file (without -C): each intensity was applied on top of the fill already shaded for the previous event, so events with the same intensity get darker and darker.

Both values are now reset for each event.

Reproduction

#!/usr/bin/env bash
# meca -A and -I carry over from one event to the next.
# Left:  only event 1 gives an alternate location (3,3), but event 2 is also moved there.
# Right: all four events have intensity -0.5, but each one is darker than the previous.
# Blue crosses mark the true event locations.
gmt begin meca_per_event png
	gmt set FONT_TITLE 13p
	gmt basemap -R-1/7/-1/7 -JX6c -Bafg -B+t"-A: newX newY only for event 1"
	gmt meca -Sa1.2c+f9p -Gred -A+p1p,red << EOF
0 0 10 0 45 90 5 3 3 Event-1
5 5 10 0 45 -90 5 Event-2
EOF
	gmt plot -Sx0.4c -W1.5p,blue << EOF
0 0
5 5
EOF
	gmt basemap -R0/8/0/2 -JX9c/3c -Baf -B+t"-I: intensity -0.5 for all events" -X7.5c -Y1.5c
	gmt meca -Sa1c -Gred -I << EOF
1 1 10 0 45 90 5 -0.5
3 1 10 0 45 90 5 -0.5
5 1 10 0 45 90 5 -0.5
7 1 10 0 45 90 5 -0.5
EOF
gmt end show

Before this PR:

After this PR:

Bugs found and fixed by Claude Opus 5.5.