make live-preview follow min or max point

[cosmicexplorer]

This makes the output buffer window's point for markdown-live-preview-mode stay at point-min or point-max, if the window displaying markdown-live-preview-buffer was already at point-min or point-max. This means the output buffer will not have to be manually re-scrolled down if the user is adding lots of text to to the bottom of a file and using live-preview.

[cosmicexplorer]

Ok, for some reason this works just fine interactively, but behaves differently in batch mode (the eternal struggle), causing the test to fail. I'll find a way to trip this appropriately.

[cosmicexplorer]

This might also fix some of the errors #69 is having too because of the fix to markdown-temp-eww. I also changed it to make sure the number of visual lines between window-point and window-start is used, instead of real lines.

Now that make evm exists, I'll fix the errors each version is having on these tests.

[cosmicexplorer]

Ok, this should work. Most of the issue was that I forgot that markdown-temp-eww doesn't actually use eww, and I forgot that the CI server sometimes doesn't have libxml2 compiled in. This should satisfy the CI server.

[jrblevin]

For some reason (featurep 'libxml2) returns nil on my Emacs (25.1.50.1 on OS X), so the test-markdown-ext/live-preview-exports fails.

[jrblevin]

The above mentioned 25.1 build was from emacsforosx.com. I tried a build of 24.5 from MacPorts and it also returns nil. Both have eww.

[cosmicexplorer]

That's because libxml2 isn't a "feature" in emacs lisp, I was going too fast and thought I remembered how libxml2 was checked. I've changed that to (fboundp 'libxml-parse-html-region), which is how eww checks whether or not it's able to parse html. That's weird that it was failing, though; it should just skip it. Can you describe what the error was? Either way, this should fix it.

[jrblevin]

Thanks. That's right--I think we saw a similar issue before, but I forgot.

I'll check this version again soon. Here's the error I got before:

Test test-markdown-ext/live-preview-exports condition:
    (ert-test-failed
     ((should-error
       (markdown-live-preview-mode))
      :form
      (markdown-live-preview-mode)
      :value t :fail-reason "did not signal an error"))
   FAILED   22/248  test-markdown-ext/live-preview-exports

[cosmicexplorer]

Oh ok, that makes sense. I was worried it was from somewhere else.

[jrblevin]

Thanks, I rebased and applied this as dda54f7.