[#561]Queries involving keys containing four backslashes ("\\") failing.

Summary of Issue

jimblackler noticed that different behavior occurs between parsing a string to create JSONObject and querying a JSONObject using JSONPointer(). There is not special handling for JSONPoiner \s in querying as mentioned in the fix for #588 .

I do think the documentation needs to be updated from

""           // the whole document
"/foo"       ["bar", "baz"]
"/foo/0"     "bar"
"/"          0
"/a~1b"      1
"/c%d"       2
"/e^f"       3
"/g|h"       4
"/i\\j"      5
"/k\"l"      6
"/ "         7
"/m~0n"      8`

to

""           // the whole document
"/foo"       ["bar", "baz"]
"/foo/0"     "bar"
"/"          0
"/a~1b"      1
"/c%d"       2
"/e^f"       3
"/g|h"       4
"/i\j"       5 // Change to demonstrate intended behavior
"/k\"l"      6
"/ "         7
"/m~0n"      8`

Summary of Changes

• Additional unit test that clarifies backslash behavior differences between JSONObject() and JSONPointer()

Expected Behavior

• No regression behavior
• All unit tests pass