add support for map type

[ananthakumaran]

I am not sure about the public API exposed by the library, so tried to keep all the exported function backward compatible.

[coveralls]

Pull Request Test Coverage Report for Build 556

• 79 of 79 (100.0%) changed or added relevant lines in 6 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

---

Totals
Change from base Build 550:	0.0%
Covered Lines:	1697
Relevant Lines:	1697

---

💛 - Coveralls

[k32]

Thanks for your PR! Could you please bump app version and add a changelog entry?

[zmstone]

unfortunately, we have a limit of maximum 80-char line width. please help to make the long lines shorter

[ananthakumaran]

I thought make elvis-rock would warn me about line length, I did fix all the errors reported by it. Btw, I didn't mean to trigger another review as I still need to address some of the review comments. I will ping you once I addressed all the comments.

[zmstone]

elvis does not check test modules.

[zmstone]

this diff should make elvis check test dir, please help to add it:

index c1391d2..7a420db 100644
--- a/elvis.config
+++ b/elvis.config
@@ -57,7 +57,15 @@
                    , {elvis_style, no_debug_call}

                  ]
-       }
+       },
+      #{dirs => ["test"],
+        filter => "*.erl",
+        rules => [ {elvis_style, line_length,
+                      #{ limit => 80,
+                         skip_comments => false
+                       }}
+                 ]
+      }
      ]
     }
    ]```

[zmstone]

@ananthakumaran Perfect PR!