Instead of `$HOME/.pandoc`, the default user data directory is
now `$XDG_DATA_HOME/pandoc`, where `XDG_DATA_HOME` defaults to
`$HOME/.local/share` but can be overridden by setting the environment
variable.
If this directory is missing, then `$HOME/.pandoc` is searched
instead, for backwards compatibility. However, we recommend
moving local pandoc data files from `$HOME/.pandoc` to
`$HOME/.local/share/pandoc`.
On Windows the default user data directory remains the same.
Closes#3582.
[API change]
* Depend on ipynb library.
* Add `ipynb` as input and output format.
* Added Text.Pandoc.Readers.Ipynb (supports both nbformat v3 and v4).
* Added Text.Pandoc.Writers.Ipynb (supports nbformat v4).
* Added ipynb readers and writers to T.P.Readers,
T.P.Writers, and T.P.Extensions. Register the
file extension .ipynb for this format.
* Add `PandocIpynbDecodingError` constructor to Text.Pandoc.Error.Error.
* Note: there is no template for ipynb.
The only thing we gained from the custom build was
automatic installation of the man page when using
'cabal install'. But custom builds cause problems,
e.g., with cross-compilation.
Installation of the man page is better handled by packagers.
Note to packagers (e.g. Debian): it may be necessary
to add a step installing the man page with the next
release.
The new Opt module has only a few dependencies. This is important for
compile-times during development, as Template Haskell containing modules
are be recompiled whenever a (transitive) dependency changes.
Disabling the flag will cause derivation of ToJSON and FromJSON
instances via GHC Generics instead of Template Haskell. The flag is
enabled by default, as deriving via Generics can be slow (see #4083).
* Lua: allow access to pandoc state
Lua filters and custom writers now have read-only access to most fields
of pandoc's internal state via the global variable `PANDOC_STATE`.
* Lua: allow iterating through fields of PANDOC_STATE
* Lua filters doc: describe CommonState
* Lua filters doc: mention global variable PANDOC_STATE
* Lua: add access to logs
Log messages can currently only be printed, but not decomposed.
