assertinitoptimizers -> assert_initoptimizers. Documentation.

Fixed version to 1.2.0 [ci-skip]

Added tests for conditional sampling

Fixed wrong result of `logproblowerbound(dbm, x)` [ci skip]

BEAM and uneven batches fixed for 1.0

Tests added for this

Added tests for more complex MDBM architectures

Fixed problem with different array types in partitioned and non-partitioned layers

Compatibility with Julia 0.5 and 0.6