cmd/scriggo: support transformation of package-less programs into programs

[zapateo]

Implement a tool that, given:

• a Scriggofile
• a Scriggo script

generates a program source code that is 100% compatible with Go.

The Scriggofile must have a limitation: packages imported using main cannot have uncapitalize or selective importing. This allow to transform

IMPORT mypkg AS MAIN

into

import . "mypkg"

The script source code must be transformed in the following ways:

• it's content must be encapsulated into a main function into a main package
• functions defined using the script syntax must be converted to function literals assigned to variables
• if the last statement of the script is an expression statement not valid in Go, such expression must be assigned to the blank identifier

[gazerro]

Support for scripts has been removed in the commit f423f04. Close this issue.