Added a test for not equals which is roughly a copy of the equals test.

js/test_cases/helpers_ne/README.md

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+Without a key parameter, neither the main block nor the else block is rendered.
+
+Literal values work in both keys and values.
+
+Can't Walk Theory
+-----------------
+
+Assuming a missing value = cantwalk and a non-existent key = cantwalk then their equality makes sense.
+
+The null tests have proven that absent parameters and missing values do not equal null and therefore it is not just making all falsey values equal.

js/test_cases/helpers_ne/input1.json

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+{
+  "str": "master",
+  "int": 7,
+  "alpha": 21,
+  "beta": "21",
+  "null": null
+}

js/test_cases/helpers_ne/main.dust

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+Testing helpers:{~n}
+str is {str}{~n}
+int is {int}{~n}
+alpha is {alpha}{~n}
+beta is {beta}{~n}
+{@ne key=str value="master"}str does not equal "master"{:else}str is equal to "master"{/ne}{~n}
+{@ne key=str value="7"}str does not equal "7"{:else}str is equal to "7"{/ne}{~n}
+{@ne key=int value="7"}int does not equal "7"{:else}int is equal to "7"{/ne}{~n}
+{@ne key=int value=7}int does not equal 7{:else}int is equal to 7{/ne}{~n}
+{@ne key=alpha value=beta}alpha does not equal beta{:else}alpha is equal to beta{/ne}{~n}
+{@ne value=beta}missing key is true{:else}missing key is false{/ne}{~n}
+{@ne value=gamma}missing key and non-existent value is true{:else}missing key and non-existent value is false{/ne}{~n}
+{@ne key=alpha}missing value is true{:else}missing value is false{/ne}{~n}
+{@ne key=gamma}missing value and non-existent key is true{:else}missing value and non-existent key is false{/ne}{~n}
+{@ne key="master" value="master"}"master" does not equal "master"{:else}"master" is equal to "master"{/ne}{~n}
+{@ne key=null}null does not equal a missing value{:else}null equals a missing value{/ne}{~n}
+{@ne key=null value=gamma}null does not equal non-existent value{:else}null equals a non-existent value{/ne}{~n}
+{@ne}no parameters is true{:else}no parameters if false{/ne}{~n}