tools: Add a mkrelease.sh script

Issue #116.
tools/mkrelease: Add a get_project_root() function

Issue #116.
tools/mkrelease: Add get_{major,minor,micro}() functions

Issue #116.
tools/mkrelease: Add get_current_version() function

Issue #116.
tools/mkrelease: add a verify_version() function

Issue #116.
tools/mkrelease: Sanity-check the given version

Issue #116.
tools/mkrelease: Add replace_version() function

Issue #116.
toole/mkrelease: Implement replace_version()

Issue #116.
tools/mkrelease: Refactor main into do_mkrelease()

Issue #116.
tools/mkrelease: Add make_release_branch()

Issue #116.
tools/mkrelease: Add make_release_tag() function

Issue #116.
tools/mkrelease: Add make_version_bump_commit() function

Issue #116.
tools/mkrelease: Fix missing args

Issue #116.
tools/mkrelease: Add more explanatory function comments

Issue #116.
tools/mkrelease: Add --allow-empty on version bump commit

Issue #116.
tools/mkrelease: Fix echo variable

Issue #116.
tools/mkrelease: Print more of the actions being performed

Issue #116.
tools/mkrelease: Silence the output of verbose commands

Issue #116.
tools/mkrelease: Ensure we're always in the top dir

Issue #116.
Bump release version for '0.0.2'