Creates an environment variable in the environment block of this program with given name and value. If a variable with this name already existed, its content will be changed to the new value.
The environment block of the program is passed on to other programs executed with RunProgram(), so this method may be used to pass on information to a program executed by this program. (The executed program may use GetEnvironmentVariable() to read the variables.)
Name$ The environment variable name. Value$ The new value for the environment variable.