Reuse Existing StringBuilder

[Fleshgrinder]

All functions construct their own StringBuilder instance, it would be great if users can pass an existing one, in case they use these functions as part of building another, bigger string.

Obviously it would be best if it would be possible to integrate seamlessly with functions like buildString in a way that users do not even have to pass in anything. However, this is impossible until we have multiple receiver support in Kotlin. But, we can add extension functions to StringBuilder instead that are almost as awesome. 😎

public fun StringBuilder.appendUpperCaseFormat(value: String, separator: Char, vararg ignore: Char): StringBuilder
public fun StringBuilder.appendUpperCamelCase(value: String, vararg ignore: Char): StringBuilder
public fun StringBuilder.appendUpperDashCase(value: String, vararg ignore: Char): StringBuilder
public fun StringBuilder.appendUpperSnakeCase(value: String, vararg ignore: Char): StringBuilder

public fun StringBuilder.appendLowerCaseFormat(value: String, separator: Char, vararg ignore: Char): StringBuilder
public fun StringBuilder.appendLowerCamelCase(value: String, vararg ignore: Char): StringBuilder
public fun StringBuilder.appendLowerDashCase(value: String, vararg ignore: Char): StringBuilder
public fun StringBuilder.appendLowerSnakeCase(value: String, vararg ignore: Char): StringBuilder