Release v1.0.0-rc2

new features:

• pkg.NewConstDecl: support iota
• unsafe.Sizeof
• unsafe.Alignof
• unsafe.Offsetof
• unsafe.Add
• unsafe.Slice
• gop parser: support mode=ParseGoFiles
• gop run support -gop: parse a .go file as a .gop file
• gop run: check isDirty to speed up
• gop run -nr: don't run if no change
• goptestgo: run all cases in GOROOT

changes:

• fix #768 #769 #770 #772 #774 #776 #778 #780 #781 #782 #784 #789 #790
• RunGoCmd: support stdin
• format: support if..else if
• TestErrVar; TestVarAfterMain (scope bugfix)
• UnderscoreFuncAndMethod