v0.5 WIP

New Features / Changes:

• Explicit ImPlotContexts and Major Refactors #48 (comment)
• Per Axis Context Menus #48 (comment)
• Styling Colors and Variables Overhaul #48 (comment)
• Built-In Style Colors #48 (comment)
• Next Item Styling Functions #48 (comment)
• Legend Popup and Drag and Drop Utilities #48 (comment)
• Candlestick Chart in Demo #81

Bug Fixes:

• make axes recover when zoom goes below epsilon #105
• fix query rect only renders if flag is set #96
• fix y-axis flags issues #90
• fix integer overflow for 32-bit ImDrawIdx #88
• make vertical text scaling and offset obey ImGui font settings #100