BSD editline and history libraries (shim development files)

 GNU readline changed its license from GPL-2 to GPL-3 with version 6,
 which excludes GPL-2-only programs from using current readline versions.
 editline resembles readline functionally and with regards to its API.
 .
 This is a development shim library that can be used to link a GPL-2-only
 program that depends on readline with editline.