v0.34.7

More updates for plot feature

• Make legend optional (Now, no legend is available)
• Implement set_line_style. Here are available line styles.
  • LineStyle::Solid
  • LineStyle::Dashed
  • LineStyle::Dotted
  • LineStyle::DashDot
• Implement set_color
• Implement set_alpha
• More markers.

Getter for ODE

• Add explicit getter for ExplicitODE and ImplicitODE for various fields.

Full Changelog: v0.34.6...v0.34.7