FEAT: adding new #export compiler directive.

Usage:

    #export [<symbols>]

    <symbols> : one or several function or global variable name
FEAT: implemented export (.edata) section support in PE emitter. Exporting both functions and global variables is supported.
FIX: added proper timestamp in PE header for DLLs.
FEAT: added generated filename to compilations result logs.
FEAT: comment removed and minor cosmetic improvements.
FIX: regression bug on code-base and data-base addresses calculation in PE header.
FEAT: ABI-compatible function prolog/epilog generation now only needs the 'callback flag (no more need to explicitly specify a cconv in function's spec).
FEAT: on-load optional callback now supported for DLLs.

Syntax:

    on-load: func [
        hinstDLL   [integer!]            ;-- handle to DLL module
        fdwReason  [integer!]            ;-- reason for calling function
        lpReserved [integer!]            ;-- reserved
        return: [logic!]
    ][
	...
	true                             ;-- true: load DLL, false: abort loading
    ]

    #export [on-load ...]

For now, 'on-load will be called twice, once on loading, once of unloading the DLL (will be separated in the next commits).

For more info, see: http://msdn.microsoft.com/en-us/library/windows/desktop/ms682596(v=vs.85).aspx
FEAT: encapsulated win32 runtime code in a namespace.
FEAT: merged changes from master branch.
FIX: local variable wrongly prefixed by namespace in path assignments.
FEAT: default entry-point routine provided.
FEAT: moved win32-specific init code in a function (allows deferred initialization for DLL).
FEAT: finalized dll callbacks handling.
FEAT: runtime init code now correctly called by DLL entry point.

Syntax:

You can now _optionally_ defined 4 callbacks when producing a DLL:

 on-load:        func [hModule [integer!][...]
 on-unload:      func [hModule [integer!][...]
 on-new-thread:  func [hModule [integer!][...]
 on-exit-thread: func [hModule [integer!][...]

 hModule is a handler on the DLL instance.

They don't need to be added to #export block.
FIX: too aggressive namespace prefixing on paths.
FEAT: moved x87 FPU init sequence in DLL init routine when compiling DLL.
FEAT: x87 previous state now saved when compiling DLL (useful to set state back on exiting some callbacks).
FEAT: added system/fpu/init virtual path to emit FPU init opcode.
FIX: removed FPU global code generation when compiling DLL.
FEAT: implemented relocation support for DLL.
FEAT: minor code refactoring.
FEAT: support optional calling convention specifier for exported functions. Will override cconv specified in function's attributes block if any.

Syntax:

    #export <cconv> [...]

    <cconv> : optional calling convention word (stdcall or cdecl)
FEAT: added -dlib command-line option for rsc compiler front-end to output a DLL.
FEAT: added sample script for DLL generation.
FIX: minor tabulation fix.