basic_string: optimize move ctor and assignment

Until now, move ctor and assignment made unnecessary copies when
non_sso was used. Fix that by just moving non_sso_data.

Example: Missing exception handling in Panaconda

Add missing catch clause to handle transaction_error

tests: change sizeof(&tls->local()) to sizeof(tls->local())

The idea is to persist tls->local() variable, not the pointer to
it.

contigous_iterator: make operator[] take signed integral instead

of unsigned.

The reason is that Windows cannot decide for a call like this:

`it[0] = 10`

whether to use:
* operator[](unsigned) -- one conversion from signed to unsigned
* operator T*() and then build in operator[](signed) -- one conversion

Example: Handle exceptions in panaconda example

Update readme

Add try-catch clauses to avoid throwing
exceptions from destructors

Example: Handle exceptions in pman example

Handle exceptions at pool close

Add try-catch clause in destructor

Add some exception handling for closing and assignments

Documentation update for pool header

vector, segment_vector: optimize clear() and erase() for trivial-types

Add missing information about exceptions

Example: Handle exceptions in pmpong example

perist() was missing.

Add try-catch clauses to avoid throwing
exceptions from destructors

replace it with std::is_trivially_destructible which is narrower but
that's fine - it means that earlier, for some types we would not call
destructors explicitly and now we will (but they will do nothing).

do not snapshot all erased elements if the are at the end.

Test: check_is_pmem unchecked return value fix

Example: Add exception handling to example

Add suppression for unchecked return value

Test: Make persistent array destructor fix

Example: Add try-catch clause around pool close function

Add missing try-catch clauses to handle proper exceptions

Avoid throwing an exception from main function

Add try-catch clause to avoid throwing
an exception from destructor on assignment

Avoid potential side effect in array_modifiers test

Move post-incrementation after assertion to avoid side effect

String capacity test - unchecked value fix

Exception handling for volatile state test

examples: add vector-based slab example