Modernise: replaces C-style casts with static_cast< >

[krishnakumarg1984]

According to this answer on stackoverflow,

• C++ style casts are checked by the compiler. C style casts aren't and can fail at runtime.
• Also, C++ style casts can be searched for easily, whereas it's really hard to search for C style casts.
• Another big benefit is that the 4 different C++ style casts express the intent of the programmer more clearly.
• When writing C++ I'd pretty much always use the C++ ones over the the C style.

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According to this answer on stackoverflow,

• static_cast<>() gives you a compile time checking ability, C-Style cast doesn't.
• static_cast<>() is more readable and can be spotted easily anywhere inside a C++ source code, C_Style cast is'nt.
• Intentions are conveyed much better using C++ casts.

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Further reading at learncpp

Although a C-style cast appears to be a single cast, it can actually perform a variety of different conversions depending on context. This can include a static cast, a const cast or a reinterpret cast (the latter two of which we mentioned above you should avoid). As a result, C-style casts are at risk for being inadvertently misused and not producing the expected behavior, something which is easily avoidable by using the C++ casts instead.
Also, because C-style casts are just a type name, parenthesis, and variable or value, they are both difficult to identify (making your code harder to read) and even more difficult to search for.

The main advantage of static_cast is that it provides compile-time type checking, making it harder to make an inadvertent error.
static_cast is also (intentionally) less powerful than C-style casts, so you can’t inadvertently remove const or do other things you may not have intended to do.

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Closes #375.