Update type definitions

Minor changes to make the type definitions more accurate

Add boolean and array to `Value` type, since `evaluate` can return those
```js
Parser.evaluate("true") // returns boolean
Parser.evaluate("[1,2,3]") // returns array
```

Update `evaluate`'s and `simplify`'s definition to only take an object of
`Value`s instead of a `Value` (which can also be array/boolean/etc.)
Update `evaluate` to return a `Value` type instead of just `number`

Add `operators.array` to the `ParserOptions`

parser.d.ts

@@ -1,6 +1,8 @@
 export type Value = number
     | string
+    | boolean
     | ((...args: Value[]) => Value)
+    | Value[]
     | { [propertyName: string]: Value };
 
 export interface Values {
@@ -51,6 +53,7 @@ export interface ParserOptions {
     max?: boolean,
     assignment?: boolean,
     fndef?: boolean,
+    array?: boolean
     cbrt?: boolean,
     expm1?: boolean,
     log1p?: boolean,
@@ -65,16 +68,16 @@ export class Parser {
     functions: any;
     consts: any;
     parse(expression: string): Expression;
-    evaluate(expression: string, values?: Value): number;
+    evaluate(expression: string, values?: Values): Value;
     static parse(expression: string): Expression;
-    static evaluate(expression: string, values?: Value): number;
+    static evaluate(expression: string, values?: Values): Value;
 }
 
 export interface Expression {
-    simplify(values?: Value): Expression;
-    evaluate(values?: Value): any;
+    simplify(values?: Values): Expression;
+    evaluate(values?: Values): Value;
     substitute(variable: string, value: Expression | string | number): Expression;
     symbols(options?: { withMembers?: boolean }): string[];
     variables(options?: { withMembers?: boolean }): string[];
-    toJSFunction(params: string | string[], values?: Value): (...args: any[]) => number;
+    toJSFunction(params: string | string[], values?: Values): (...args: any[]) => Value;
 }