RFR: 278: Enhance the /solves command

[Robin Westberg]

Hi all,

Please review this change that improves the allowed syntax for the `/solves` command.

Best regards,
Robin

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Commit messages:
 - Initial implementation

Changes: https://git.openjdk.java.net/skara/pull/556/files
 Webrev: https://webrevs.openjdk.java.net/skara/556/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-278
  Stats: 281 lines in 6 files changed: 236 ins; 18 del; 27 mod
  Patch: https://git.openjdk.java.net/skara/pull/556.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/556/head:pull/556

PR: https://git.openjdk.java.net/skara/pull/556