Polymake.jl 0.7.1 released

Today Polymake.jl 0.7.1 has been released.

Diff since v0.7.0

Closed issues:

• Race-conditions with scratchspaces (#381)
• Polymake scratch space is regenerated twice each time I load Oscar (#384)
• Matroid NON_BASES (#388)

Merged pull requests:

• QuadraticExtension and corresponding container types (#389) (@alexej-jordan)
• Graph: Attach EdgeMap<Graph<*>, Int> (#390) (@lkastner)
• bump to 0.7.1, require lib 0.8 for graphmaps and quadraticextension (#391) (@benlorenz)