UI restructure: use a global variable to hold the dive we show / edit

There is massive confusion about what we display when and where and which
dive structure (or pointer to a dive structure) contains which information
at which stage. This is the first step towards restructuring all of this.

This creates a global variable displayed_dive which at any point in time
should be what is displayed on screen (both in the profile and in the
maintab). It removes the editedDive concept from MainTab.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

dive.c

@@ -8,6 +8,11 @@
 #include "dive.h"
 #include "libdivecomputer.h"
 
+/* one could argue about the best place to have this variable -
+ * it's used in the UI, but it seems to make the most sense to have it
+ * here */
+struct dive displayed_dive;
+
 struct tag_entry *g_tag_list = NULL;
 
 static const char *default_tags[] = {