Added feature - to set default value for var

This is a feature add, which allows you to declare default value to a class variable.

For example
Screen=(
    var color="black"
    var bgcolor="white"
    var width=300
    var height=200
    var title
    function show
    function hide
    function resize
)

Now when we create a new object
new Screen S1

By default the Class variable:
    color is set to "black"
    bgcolor is set to "white"
    width is set to "300"
    height is set to "200"

But Class variable: title is not initialized to any value

If you want you can write your Screen::__init__() function
to override default values if parameters are passed during creation of new object.
Update src/baboosh.sh
Added feature - readonly class variable

This is a feature add, which allows you to declare a readonly class variable

Syntax:

Human=(
    var name
    var age

    # Read only variable with default value
    readonly:var eyes=2

    # Read only variable ( no default value - value to be set at __init__ )
    readonly:var gender
    function eat
    function sleep
}


In the above example Humans created with readonly variable 'gender'
In this case variable gender must be set in __init__ without fail.

Once the value is set to a readonly:var it can be read like a normal var
Added _meta_destroy_obj_aliases

Removes the aliases created for specific object.

Automatically invoked when script exits or killed
Can be invoked manually by using obj.die
Merge pull request #2 from nischithbm/master

Added feature - to set default value for var