Add backend using avro data files

[drussel]

Add backend using avro data files

[drussel]

We probably need to ship avro as part of rmf. Can use something like this to test if it is there, and then subdir it if it is not already there.

- Try to find ImageMagick++

Once done, this will define

Magick++_FOUND - system has Magick++

Magick++_INCLUDE_DIRS - the Magick++ include directories

Magick++_LIBRARIES - link these to use Magick++

include(LibFindMacros)

Dependencies

libfind_package(Magick++ Magick)

Use pkg-config to get hints about paths

libfind_pkg_check_modules(Magick++_PKGCONF ImageMagick++)

Include dir

find_path(Magick++_INCLUDE_DIR
NAMES Magick++.h
PATHS ${Magick++_PKGCONF_INCLUDE_DIRS}
)

Finally the library itself

find_library(Magick++_LIBRARY
NAMES Magick++
PATHS ${Magick++_PKGCONF_LIBRARY_DIRS}
)

Set the include dir variables and the libraries and let libfind_process do the rest.

NOTE: Singular variables for this library, plural for libraries this this lib depends on.

set(Magick++_PROCESS_INCLUDES Magick++_INCLUDE_DIR Magick_INCLUDE_DIRS)
set(Magick++_PROCESS_LIBS Magick++_LIBRARY Magick_LIBRARIES)
libfind_process(Magick++)

[drussel]

The current big issue is the lack of seek(), sync() support in DataFileReader and append in DataFileWriter.