macros for modules

[somucheffort]

for a sake of speeding development up modules would have macros-involved functions, which would tell to export them.
so modules would not require to export whole map that includes all possible values to export.

#[export("argv")]
pub fn get_argv() { /*...*/ }

#[export("float")]
pub fn get_float_random_name() { /*...*/ }

[somucheffort]

closed. see #10