markdown: Add .Links action and flattened metadata structure

.Links available only for generated sites and variables no longer in a [variables] category in metadata (flat structure).

Fix more race conditions.

Fix race condition on parsers.
Added page links generator.

Test setup func for fastcgi.go

markdown: Change metadata variables type to map[string]string

Instead of map[string]interface{}

from map[string]interface{} to map[string]string

Open a redir block to bulk-specify a bunch of redirects that share a status code

markdown, browse: Integrated Context struct for templating

Put the title into the .Doc variables as well.
Changed the test template file to use new names.

This is a breaking change for those who expect catch-all redirects to preserve path; use {uri} variable explicitly now

browse: Save sorting preferences as cookies

To be used across directories

Changed the tests accordingly.

initial test for config/setup/fastcgi.go

Created a struct containing middleware.Context, Title, Markdown and the
variables from the user to use to render the template.
The title now can be accessed via {{.Title}}.
The variables can now be accessed via {{.Var.myVariableName}}.

specify go versions to use via travis

Created sample files for the test

Moved the Context type to middleware and exported it.
Users can use .Include and others in browse directive templating
Created test for the templates directive.