Compiler macros

The following macros are defined by the build tools. These macros may be used to control conditional compilation.

`__SYMBIAN32__`	indicates Symbian OS code in general
`__WINS__`	indicates the WINS or WINSCW platforms
`__DLL__`	if applicable, indicates that a DLL is being built
`__EXE__`	if applicable, indicates that a `.exe` is being built
`__CW32__`	indicates CodeWarrior is the compiler
`__EPOC32__`	indicates any target hardware platform, regardless of processor type or hardware architecture

Further macros can be defined in project files through the MACRO statement.