Allow user to customise available global variables

[paulcuth]

Add an array to the configuration object called libs. If present, parse the values in order and add/remove global vars according to the following rules:

value	action
*	Add all global methods and namespaces
.propName	Add the propName global method only
libName	Add the libName namespace and all its properties
libName.propName	Add the propName property of libName only
-libName	Remove libName namespace and therefore all its properties
-libName.propName	Remove propName property of libName only

Examples:

[ '*', '-window' ]
All libs except window.

['.setmetatable', 'table']
setmetatable() and all of the table lib only.

['string', '-string.reverse']
Only the string lib without string.reverse().

[paulcuth]

Please add a thumbsup reaction if you'd like to see this feature, this'll help me to prioritise.