larsrh/libisabelle: libisabelle 1.0.0-RC3

Major changes (since 0.9.3)

• drop pre-Isabelle2017 support (55a96af)
• add Isabelle2018-RC2 support (a36e9d7)

• dependency bumps (6b8e385, 5ab91d6, 9292571, fbb97a3)
• tighter checks when loading resources from classpath (55a496f, #69)
• allow symlinked local storage (69b413c, #71)

• tests are automatically run with the latest supported Isabelle version (52e1c85)
• package sizes trimmed (d4087ed, fixed in 27a2c852)
• fix cross-publishing (#68, 803410d)
• future: support for further release candidates of Isabelle2018 will be added to this release; pide-package cannot be updated however
• no more multi-isabelle dependency (84b4f18, #70)