Juno Improvements: type inference and intrinsics

juno_frontend/examples/intrinsics1.jn

juno_frontend/examples/intrinsics2.jn

juno_frontend/examples/intrinsics3.jn

juno_frontend/src/codegen.rs

juno_frontend/src/intrinsics.rs

juno_frontend/src/lang.l

juno_frontend/src/lang.y

juno_frontend/src/locs.rs

juno_frontend/src/main.rs

juno_frontend/src/semant.rs

juno_frontend/src/types.rs