Prepare CHANGELOG for v1.20.0 release
## [Unreleased]
+## 1.20.0 - 2017-08-10
+
+### Fixed
+
+* `HandleExitCoder` is now correctly iterates over all errors in
+ a `MultiError`. The exit code is the exit code of the last error or `1` if
+ there are no `ExitCoder`s in the `MultiError`.
+* Fixed YAML file loading on Windows (previously would fail validate the file path)
+* Subcommand `Usage`, `Description`, `ArgsUsage`, `OnUsageError` correctly
+ propogated
+* `ErrWriter` is now passed downwards through command structure to avoid the
+ need to redefine it
+* Pass `Command` context into `OnUsageError` rather than parent context so that
+ all fields are avaiable
+* Errors occuring in `Before` funcs are no longer double printed
+* Use `UsageText` in the help templates for commands and subcommands if
+ defined; otherwise build the usage as before (was previously ignoring this
+ field)
+* `IsSet` and `GlobalIsSet` now correctly return whether a flag is set if
+ a program calls `Set` or `GlobalSet` directly after flag parsing (would
+ previously only return `true` if the flag was set during parsing)
+
+### Changed
+
+* No longer exit the program on command/subcommand error if the error raised is
+ not an `OsExiter`. This exiting behavior was introduced in 1.19.0, but was
+ determined to be a regression in functionality. See [the
+ PR](https://github.com/urfave/cli/pull/595) for discussion.
+
+### Added
+
+* `CommandsByName` type was added to make it easy to sort `Command`s by name,
+ alphabetically
+* `altsrc` now handles loading of string and int arrays from TOML
+* Support for definition of custom help templates for `App` via
+ `CustomAppHelpTemplate`
+* Support for arbitrary key/value fields on `App` to be used with
+ `CustomAppHelpTemplate` via `ExtraInfo`
+* `HelpFlag`, `VersionFlag`, and `BashCompletionFlag` changed to explictly be
+ `cli.Flag`s allowing for the use of custom flags satisfying the `cli.Flag`
+ interface to be used.
+
+
## [1.19.1] - 2016-11-21
### Fixed
