Move SDL includes so that all files include them.
Fix warnings for Visual Studio.
GCC warnings.
Remove old commented out code.
Eliminate warnings.
Use vectors declared in classes rather than allocating separately.
Remove old commented out code.
Eliminate more warnings.
Added in-game music; also have separate options for saving music and sound, and make music fade out.
Add speech samples - see https://github.com/rhunter/gigalomania/commit/02214e2181258151f03a9a03830bbf22f37afceb for details.
Add all samples to Git repository.
Fixes for game music and Android.
fix warnings: writable string literals

Seen in CLang as:
  conversion from string literal to 'char *' is deprecated [-Wdeprecated-writable-strings]

Replaced `putenv("X=Y")` with `setenv("X", "Y", 1)` as recommended in the
getenv(3) man page, which states "The setenv() function is strongly preferred
to putenv()."
fix warnings: implicit conversion of NULLs

Seen in CLang as:
  warning: implicit conversion of NULL constant to 'bool' [-Wnull-conversion]
fix warnings: writable string literals

Seen in CLang as:
  conversion from string literal to 'char *' is deprecated [-Wdeprecated-writable-strings]

The SDL2_image code is written in C, and C compilers treat string literals as
mutable (non-constant) by default.

C++98 deprecated writable string literals and C++11 made them an error.

There's no reason the upstream C code couldn't also add a couple of `const`
hints for the compiler.
gui panels: removed unused caller_button field

Raised in CLang as:

    warning: private field 'caller_button' is not used [-Wunused-private-field]

The OneMouseButonPanel class declared a private field `caller_button` which
CLang thought was unused. Although caller_button is passed in to
OneMouseButtonPanel constructors and methods, the value is used immediately
(not stored in a field).