Initiate port to C99.

Start by compiling with "-std=c99" by default.
Convert for-loops to C99-style loops.
Move several definitions to their first use.

Move variable definitions to their first use (or to where they are initialised),
for two reasons:

- it allows the use of "const" in several cases, and
- it is more readable (or at least more succinct) by keeping variable
  definitions close to where they are used.

For example, the variable "data" is used in a very limited scope (it is
allocated and freed within less than two dozen lines), so I think it makes sense
to move its definition to where it is first used.
Use the "restrict" keyword where possible.
Convert as many pointers as possible to VLAs.

Replacing pointers with VLAs avoids the necessity of making sure to free() them.
blockread: store the input file name in a VLA.

This avoids various calls to free() and hence potential errors.
Make some minor stylistic changes.
Initialise an array with an initialiser list.
Init sf_file_info with a designated initialiser.
SConstruct: update to work correctly on Windows.

Update the SCons based build system to work correctly on Windows.  This entails
overriding the default tools on Windows to not include the Microsoft tools,
because msndfile requires C99 support and the Visual Compiler does not (and most
likely will not ever) support that.

Furthermore, most of the Windows/Unix special-casing has become unnecessary,
including the "--force-mingw" option, which has therefor been removed.
compile_msndfile: update to work on Windows.

Due to the requirement of C99 support, HaveStdintH now defaults to "true", and
the compiler is now assumed to support gcc-style options.
Docs: update the manual.
Add a ChangeLog entry for the coming 1.1 release.
Remove unused tools from default.py.
default.py: add a platform argument to tool_list().
Merge branch 'c99_conversion'

* c99_conversion:
  default.py: add a platform argument to tool_list().
  Remove unused tools from default.py.
  Add a ChangeLog entry for the coming 1.1 release.
  Docs: update the manual.
  compile_msndfile: update to work on Windows.
  SConstruct: update to work correctly on Windows.
  Init sf_file_info with a designated initialiser.
  Initialise an array with an initialiser list.
  Make some minor stylistic changes.
  blockread: store the input file name in a VLA.
  Convert as many pointers as possible to VLAs.
  Use the "restrict" keyword where possible.
  Move several definitions to their first use.
  Convert for-loops to C99-style loops.
  Initiate port to C99.

Conflicts:
	CHANGELOG