v0.7.4

ReachabilityAnalysis v0.7.4

Diff since v0.7.3

Merged pull requests:

• Add LGG09 algorithm using expv (#246) (@mforets)
• Update README.md (#247) (@mforets)
• Add HalfSpace and Hyperplane symbolic constructors (#248) (@mforets)
• fix a bug in nomalization of CS (#249) (@mforets)
• Fix tspan for hybrid flowpipes (#250) (@mforets)
• fix eval functions for hybrid flowpipes (#251) (@mforets)
• Update discretization (#255) (@mforets)