Import feature for modular emerald.

[armcburney]

section.emr

section
  h1 This is some modular html.

main.emr

body
  import section
  import section

=>

body
  section
    h1 This is some modular html
  section
    h1 This is some modular html

[armcburney]

Going to remove this from the v1 Release - this feature can be added at the same time we add components.