As discussed in #8054 and #8136, org doesn't always export links correctly if
the syntax deviates from the one given on the org mode website. This results
in broken links on github and/or spacemacs.org as in #6722, #8036, #8054, #7956
and possibly others.
This modifies all links not already fixed in #8136. Internal links are
handled with Custom IDs. External file links are formatted according to org
guidelines as well (see bottom), and if they point to a specific headline in an
external file, a custom ID is created as well.
Fixes#6722, #8036, #7956, #7916 as well as other unreported broken
links.
http://orgmode.org/manual/External-links.html#External-linkshttp://orgmode.org/manual/Internal-links.html#Internal-links
TODO: make Custom IDs invisble in space-org-mode
This make `SPC h SPC` as default binding for accessing `helm-spacemacs`,
by either A) changing all the documentation; and B) adding a deprecation
message for `SPC f e h`.
The deprecation use a warning, because if a message is used it's hidden
directly when the helm buffer is shown, making it nearly unnoticeable
for the user.
