Rhai extensions

Besides the basic Rhai features, these are the modules/behaviors defined:

variable::is_set(name: &str) -> bool

Returns true if the variable/placeholder has been set for the template
variable::get(name: &str) -> value

Gets any defined variable in the Liquid template object
variable::set(name: &str, value: (&str|bool))

Set new or overwrite existing variables. Do not allow to change types.

variable::prompt(text: &str, default_value: bool) -> value

Prompt the user for a boolean value
variable::prompt(text: &str) -> value

Prompt the user for a string value
variable::prompt(text: &str, default_value: &str) -> value

Prompt the user for a string value, with a default already in place
variable::prompt(text: &str, default_value: &str, regex: &str) -> value

Prompt the user for a string value, validated with a regex
variable::prompt(text: &str, default_value: &str, choices: Array) -> value

Prompt the user for a choice value

file::exists(path: &str)

Test if a path exists
file::rename(from: &str, to: &str)

Rename one of the files in the template folder
file::delete(path: &str)

Delete a file or folder inside the template folder
file::write(file: &str, content: &str)

Create/overwrite a file inside the template folder
file::write(file: &str, content: Array)

Create/overwrite a file inside the template folder, each entry in the array on a new line

system::command(cmd: &str, args: Array) -> value

Execute a command on the system generating the project from a template.

The user will be prompted with
```
The template is requesting to run the following command. Do you agree?
<command> <args>
```
unless the user uses the flag --allow-commands. If the user attempts to use the --silent flag without the --allow-commands flag will fail.
system::date() -> Date

Get the date in UTC from the system as an object with the properties year, month, and day.

to_kebab_case(str: &str) -> String

"We are going to inherit the earth." => "we-are-going-to-inherit-the-earth"
to_lower_camel_case(str: &str) -> String

"It is we who built these palaces and cities." => "itIsWeWhoBuiltThesePalacesAndCities"
to_pascal_case(str: &str) -> String

Same as to_upper_camel_case(str: &str) -> String
to_shouty_kebab_case(str: &str) -> String

"We are going to inherit the earth." => "WE-ARE-GOING-TO-INHERIT-THE-EARTH"
to_shouty_snake_case(str: &str) -> String

"That world is growing in this minute." => "THAT_WORLD_IS_GROWING_IN_THIS_MINUTE"
to_snake_case(str: &str) -> String

"We carry a new world here, in our hearts." => "we_carry_a_new_world_here_in_our_hearts"
to_title_case(str: &str) -> String

"We have always lived in slums and holes in the wall." => "We Have Always Lived In Slums And Holes In The Wall"
to_upper_camel_case(str: &str) -> String

"We are not in the least afraid of ruins." => "WeAreNotInTheLeastAfraidOfRuins"