C++ Naming Style is not consistent for Methods

[jenisys]

By looking over the current state of implementation of this repository,
I noticed that the C++ naming style seems to be not consistent related to methods:

• lvglpp::LvDisplay::Rotate() method
• lvglpp::LvDisplay::getWidth() method (counter-example in same class)
• lvglpp::LvScr::Load() method
• …

Most method names that I have seen start with lowercase letter (using camelCase).
The ones above start with uppercase letter (using CamelCase).

DESIRED:

• Use one naming scheme consistently
• Correct the few exceptions where the method name starts with uppercase letter (because most methods start with lower case letter).