- dropped build scripts and files for single-file distribution.
- updated git pre-commit hook to run "make check" instead of "make dist"
- renamed zero-input-framework to zero-input. This is to conform "there
  should be a library with the same name as package name" rule.
- rename .el.in to .el.tpl.
  melpa build process will do something on .el.in, which I do not expect.
- "make tar" is a little messy because emacs doesn't support git archive
  generated tar file.
- add zero-input-pkg.el in git, melpa build hangs when this file is not
  present.

since this is a backward incompatible change, I set version to v2.0.0.
all symbols and functions is now prefixed with zero-input.

This change is suggested by melpa reviewer.

only run check on master branch.
pkg branch is just for zero.el distribution.

minor, update doc.

- renamed zero.el back to zero-framework.el
- to build a dist, just run "make".
  the zero.el template is in zero.el.in
- zero.el is built and added to git repo in git pre-commit hook. it will
  be kept in master branch.
- fixed a few package-lint style warning.

- fix almost all checkdoc problems. the rest I don't know how to fix.
- add git pre-commit hook