implement uc_mem_unmap with snapshots

still has todos and need tests

include/uc_priv.h

@@ -289,6 +289,8 @@ struct uc_struct {
     uc_memory_mapping_t memory_mapping;
     uc_memory_filter_t memory_filter_subregions;
     uc_mem_unmap_t memory_unmap;
+    uc_mem_unmap_t memory_moveout;
+    uc_mem_unmap_t memory_movein;
     uc_readonly_mem_t readonly_mem;
     uc_cpus_init cpus_init;
     uc_target_page_init target_page;
@@ -412,6 +414,7 @@ struct uc_struct {
     PVOID seh_handle;
     void *seh_closure;
 #endif
+    GArray *unmapped_regions;
     int32_t snapshot_level;
 };