Improve formatting, primarily by:
* Adding links to relevant commands, properties, generators, and so on.
* Converting code, symbols, paths, and so on to fixed-width fonts.
* Hard wrapping lines to 80 characters or less.
Extend sentences in other documentation linking to this manual to
say that it has a list of supported compilers.
Co-Author: Brad King <brad.king@kitware.com>
Link to it from the documentation of related properties, variables
and commands.
Extend the cmake-developer(7) documentation with notes on
extending feature support for compilers.
Add properties and variables corresponding to CXX equivalents.
Add features for c_function_prototypes (C90), c_restrict (C99),
c_variadic_macros (C99) and c_static_assert (C11). This feature
set can be extended later.
Add a <PREFIX>_RESTRICT symbol define to WriteCompilerDetectionHeader
to conditionally represent the c_restrict feature.
