Move DiveList related methods/classes to own file.

The DiveList classes were a partial mess (and some of it is still in a
messy state). The classes that deal with it where done in 'qtHelpers.h',
the extern global variable in dive.h, a few methods here and there. This
concentrates most - but not all - functions in their own file. The reason
for that is to make the new developer faster when looking for things: if
it's a divecomputer related method, it should be in a single file, not
scattered around.

Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

CMakeLists.txt

@@ -104,6 +104,7 @@ SET(SUBSURFACE_CORE_LIB_SRCS
 	gettextfromc.cpp
 	#dirk ported some core functionality to c++.
 	qthelper.cpp
+	divecomputer.cpp
 )
 
 #the interface, in C++