First steps towards removing glib dependencies

- remove the build flags and libraries from the Makefile / Configure.mk
- remove the glib types (gboolean, gchar, gint64, gint)
- comment out / hack around gettext
- replace the glib file helper functions
- replace g_ascii_strtod
- replace g_build_filename
- use environment variables instead of g_get_home_dir() & g_get_user_name()
- comment out GPS string parsing (uses glib utf8 macros)

This needs massive cleanup, but it's a snapshot of what I have right now, in
case people want to look at it.

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

libdivecomputer.h

@@ -24,7 +24,7 @@ typedef struct device_data_t {
 	dc_device_t *device;
 	dc_context_t *context;
 	int preexisting;
-	gboolean force_download;
+	bool force_download;
 } device_data_t;
 
 const char *do_libdivecomputer_import(device_data_t *data);