Release of PHP Extension v5.0.18

This is the first stable release of the new major version of the Tideways extension. We are now soft-releasing it to customers that are starting a new trial and to all existing customers that update their deb/rpm package endpoints to the new URLs.

• BC Break: TidewaysProfiler::watchCallback API now needs to return the whole $span object instead of the ID.
• BC Break: tideways.framework= cannot be set to a function name anymore, you need to dynamically call TidewaysProfiler::detectTransactionFunction($functionName) and TidewaysProfiler::detectExceptionFunction($functionName) instead now.
• Improvement: Reduce overhead of regular tracing by implementing more optimized data structures, hooks and use of Zend Engine 3 (PHP 7) APIs.
• Improvement: Automatically detect frameworks so that tideways.framework INI setting is not needed anymore.
• Improvement: Remove 1500 span limit by implementing batching and filtering of short spans.
• Improvement: Add circuit breaker that stops profiling when PHP process reaches memory usage of 90% of the configured memory limit.
• Feature: Add instrumentation for filesystem I/O using a global timer per trace (ex: 20% of 200ms trace where spent in filesystem I/O).
• Feature: Add extremely low overhead monitoring mode instrumentation for all layers, allowing to show global application performance for SQL, Caches, HTTP and others.
• Feature: Add support for memory profiling using memory_get_peak_usage() in timeline and callgraph profiler