Address the review: null inline nodes, trait spelling, and max() in json_view

- inline_nodes is null when the document has no inline nodes, instead of
  pointing past the end of the allocation; shrink_to_fit() no longer
  passes it to memcpy() for an empty node array
- is_byte_char and is_wide_char use conjunction/disjunction, which
  astyle leaves unspaced
- append_stream() uses (std::max) for the count read

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

include/nlohmann/json_view.hpp

@@ -443,7 +443,10 @@ class basic_json_document
 
         if (shrink_nodes)
         {
-            std::memcpy(fresh, d.nodes, d.node_count * sizeof(node));
+            if (d.node_count != 0)
+            {
+                std::memcpy(fresh, d.nodes, d.node_count * sizeof(node));
+            }
             ::operator delete (d.nodes);
             d.nodes = fresh;
             d.node_capacity = into_header ? d.inline_capacity : d.node_count;