Always use RFC3339 for version date format.

Fixes #695 reported by @synful.

- No longer tries to load a configuration.
- Because of this the version tests are no longer necessary.
Remove Println that panics in test
Correct URL of the favicon in the documentation

img/favicon.png does not seem to exist,
so follow the example in docs/layouts/index.html
and use /favicon.ico instead.
Docs: Quote <!--more--> in <code> instead of italicizing it

Also replace "--" with "&#x2d;&#x2d;" prevent "--" from
being interpreted as en-dash.

Note: A simple `<!--more-->` does not work.
Docs: Minor copyediting/proofreading

- Correct some typos
- Add backticks and commas where necessary
- Use fenced code blocks specifying "bash" as the language
  to avoid weird highlighting
- Place commas outside of quotation marks surroundingn codes
  to avoid possible confusion
- Suggest users to use the discussion forum rather than the
  mailing list
Fix front matter for 'Creating a New Theme'

There seems to be an issue with TOML and certain menu structures. Current workaround: YAML.
Add an `install` target to Makefile.
Add timezone to buildDate
Fix various Windows-issues

File handling was broken on Windows. This commit contains a revision of the path handling with separation of file paths and urls where needed.

There may be remaining issues and there may be better ways to do this, but it is easier to start that refactoring job with a set of passing tests.

Fixes #687
Fixes #660
ERROR-log on symbolic links

filepath.Walk does not follow symbolic links.
There's no easy fix for that outside of Go, so the best we can do for now is to give notice to the end user by ERROR log statements.

This commit also fixes a related panic situation in GenerateTemplateNameFrom when the layout dir was a symbolic link.

Fixes #283
Make Urls in menus respect CanonifyUrls

Fixes #519
Revert "Make Urls in menus respect CanonifyUrls"

This reverts commit 3ccb3979028aafb3e6cc16d47daa77a1fdea11fa.
Merge commit '9b04c279984cd236c623e8fe52603c9e6ac9d486'

* commit '9b04c279984cd236c623e8fe52603c9e6ac9d486':
  Revert "Make Urls in menus respect CanonifyUrls"
  Make Urls in menus respect CanonifyUrls
  ERROR-log on symbolic links
  Fix various Windows-issues
  Add timezone to buildDate
  Add an `install` target to Makefile.
  Fix front matter for 'Creating a New Theme'
  Docs: Minor copyediting/proofreading
  Docs: Quote <!--more--> in <code> instead of italicizing it
  Correct URL of the favicon in the documentation
  Remove Println that panics in test
  Always use RFC3339 for version date format.