0.4.0

Major changes:

• The profiler can now be compiled on Rust stable, with the caveat that the shadow stack based unwinding will be then disabled.
• The profiler is now fully lazily initialized; if disabled with MEMORY_PROFILER_DISABLE_BY_DEFAULT the profiler will not initialize itself nor create an output file.
• The signal handler registration can now be disabled with MEMORY_PROFILER_REGISTER_SIGUSR1 and MEMORY_PROFILER_REGISTER_SIGUSR2.
• When the profiling is disabled at runtime it will more thoroughly deinitialize itself, and when reenabled it will create a new output file instead of continuing to write data to the old one.
• The embedded server is now disabled by default and can be reenabled with the MEMORY_PROFILER_ENABLE_SERVER environment variable.
• The base port of the embedded server can now be set with the MEMORY_PROILER_BASE_SERVER_PORT environment variable.
• The MEMORY_PROFILER_OUTPUT now supports an %n placeholder.
• The GUI has now a graph which shows allocations and deallocations per second.