Provide predefined template type

[ayan-b]

Since moban supports user-defined template type, we can provide users with some predefined template types. The most obvious one being latex. Needs discussion on the possible syntax.

[ayan-b]

What do you think about the syntax?

[chfw]

This issue could be by-product of the resolution of #126

Imagine #126 be implemented, moban python package should then include a list of yaml files which provides custom template definitions, etc. One of them could be latex definition. I would think it will looks no different to its current form:

latex.yaml

configuration:
  template_types:
    latex:
      ..
      (ayan-b, could you fill these blanks)
      ..

Then, in user's moban file:

overrides:
   latex.yaml: configuration

[ayan-b]

Yup, this is a good idea. I am assigning that issue to myself.