Remove the ability to 'Import' .SDA files

We can instead 'Open' these files as they are just bastardized XML files.

This gets us back to a more consistent point where 'Import' gets data
directly from the dive computer (and hopefully soon we will add the
ability to load a dive directly from a uemis SDA to libdivecomputer),
and 'Open' loads a file from the filesystem of the computer we are
running on (this last sentence phrased so awkwardly as the uemis Zurich
SDA is a computer and presents a file system when connected via USB - it
just doesn't have the dive data in an accessible format in that file
system).

As a bonus we get to throw away quite a bit of code (the uemis specific
file handling, mini-XML parser with helper functions, the file open dialog
in the importer). Yay!

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

uemis.h

@@ -3,12 +3,8 @@
 
 /*
  * defines and prototypes for the uemis Zurich SDA file parser
- * we add this to the list of dive computers that is supported
- * in libdivecomputer by using a negative value for the type enum
  */
-#define DEVICE_TYPE_UEMIS (-1)
 
-void uemis_import();
 void uemis_parse_divelog_binary(char *base64, void *divep);
 
 #endif /* DIVE_H */