v0.0.4

Overview

• Added 2 new operators: group_by and flat_map
• Optimized subject related code
• Reduced observable size for MSVC
• Code simplifications

What's Changed

• Extract subscribe by @victimsnino in #154
• Empty base optimization by @victimsnino in #158
• Speedup subject by @victimsnino in #159
• group_by operator by @victimsnino in #164
• flat map implementation by @victimsnino in #165

Full Changelog: v0.0.3...v0.0.4