0.8.0 (#63)

Compared to v0.7.3

• Add UsingExecWarning when exec is used to retrieve func for argname().
• Remove NonVariableArgumentError. Use ImproperUseError instead.
• Add VarnameError and VarnameWarning as root for varname-related exceptions and warnings, respectively.
• Default strict to True for varname(), helpers.register() and helpers.Wrapper()
• Limit number of context lines for showing where ImproperUseError happens

Compared to v0.7.0

• Add UsingExecWarning when exec is used to retrieve func for argname().
• Remove NonVariableArgumentError. Use ImproperUseError instead.
• Add VarnameError and VarnameWarning as root for varname-related exceptions and warnings, respectively.
• Add strict mode to varname(), helpers.register() and helpers.Wrapper() (#57)
• Support the walrus operator (:=) (#58)
• Change argname() to accept argument names instead of arguments themselves
• Remove pos_only argument from argname()
• Add ignore argument to argname() to ignore intermediate frames
• Limit VarnameRetrievingError to the situations only when the AST node is not able to be retrieved.