map: use value semantics for MapLocation

This makes memory management more simple, as not explicit deletion
is necessary.

A rather large commit, because changing QVector<> to std::vector<>
is propagated up the call chain.

Adds a new range_contains() helper function for collection
types such as std::vector<>. I didn't want to call it
contains(), since we already have a contains function
for strings and let's keep argument overloading simple.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

core/subsurface-string.h

@@ -2,6 +2,7 @@
 #ifndef SUBSURFACE_STRING_H
 #define SUBSURFACE_STRING_H
 
+#include <algorithm>
 #include <stdbool.h>
 #include <string.h>
 #include <time.h>