moved scarpet docs to markdown files

docs/scarpet/language/VariablesAndConstants.md

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+# Variables and Constants
+
+`scarpet` provides a number of constants that can be used literally in scripts
+
+*   `null`: nothing, zilch, not even false
+*   `true`: pure true, or just 1 (one)
+*   `false`: false truth, or true falsth, 0 (zero) actually
+*   `pi`: for the fans of perimeters, its a perimeter of an apple pi of diameter 1\. About 3.14
+*   `euler`: clever guy. Derivative of its exponent is goto 1\. About 2.72
+
+Apart from that, there is a bunch of system variables, that start with `_` that are set by `scarpet` built-ins, 
+like `_`, typically each consecutive value in loops, `_i` indicating iteration, or `_a` like an accumulator 
+for `reduce` function. Certain calls to Minecraft specific calls would also set `_x`, `_y`, `_z`, indicating 
+block positions. All variables starting with `_` are read-only, and cannot be declared and modified in client code.
+
+## Literals
+
+`scarpet` accepts numeric and string liters constants. Numbers look like `1, 2.5, -3e-7, 0xff,` and are internally 
+represented as Java's `double` but `scarpet` will try to trim trailing zeros as much as possible so if you need to 
+use them as intergers, you can. Strings using single quoting, for multiple reasons, but primarily to allow for 
+easier use of strings inside doubly quoted command arguments (when passing a script as a parameter of `/script fill` 
+for example, or when typing in jsons inside scarpet to feed back into a `/data merge` command for example. 
+Strings also use backslashes `\` for quoting special characters, in both plain strings and regular expressions
+
+<pre>
+'foo'
+print('This doesn\'t work')
+nbt ~ '\\.foo'   // matching '.' as a '.', not 'any character match'
+</pre>