Test RASBASE durability

[Dimitar Misev]

Motivated by the database corruption issues reported in #1014, I'm proposing to develop a RASBASE stress test.

This is a rough sketch:

• let W be a set of representative insert and update queries
• let R be a set of representative select queries R
• test execution:
  1. a random query from W is executed, with random queries from R in parallel
  2. rasserver is killed with SIGKILL at a random point of time (perhaps other signals as well)
  3. rasdaman is restarted, and checked for consistency
  4. repeat