... instead of running a sed script over a lot of files on each
version increment.

Because executable_path and loader_path are just too inflexible for some
stuff. The rpath is supposed to be set to the Qt Creator app's Contents
folder.
Compiling on 10.4 now requires to enter compatibility mode via
QTC_TIGER_COMPAT env variable or TIGER_COMPAT_MODE qmake variable.

qtLibraryTarget is only defined if used with TEMPLATE=lib, which makes
it fail in pri files that are used for app pro files. The tests still
don't run because of run time linking issues.

Precompiled headers are a performance feature supported by some
compilers to reduce the (re-)compilation time substantially.
Usage in Qt: http://doc.qt.nokia.com/4.7/qmake-precompiledheaders.html



Due to the usage of precompiled headers Qt without demos/examples/webkit
etc might be compiled even faster than Qt Creator on some systems.
Despite of Qt, Qt Creator consist of mostly quite small subprojects
(plugins and libraries) where the effect would not be so noticeable
but still will be visible.

This patch adds default precompiled headers to any plugin and library
(i.e. by changes in src/qtcreatorplugin.pri and src/qtcreatorlibrary.pri
respectively). Almost the same headers are included to general
precompiled header (src/shared/qtcreator_pch.h) like used in QtCore,
just QPointer/QScopedPointer etc and QDebug are added, it is used almost
in any subproject. Also for plugins some QtGui related headers are added
(src/shared/qtcreator_gui_pch.h).

Default precompiled headers are enabled so:

isEmpty(PRECOMPILED_HEADER):PRECOMPILED_HEADER = $$PWD/shared/header.h

So it is possible to override this variable in any place in the project
file in case if it will be needed.

Such overriding is used for Botan (src/libs/3rdparty/botan) - it is
not a Qt project, just a pure C++. Most usable headers were used to
create special precompiled header for Botan. It is 3rd party component
so also src/libs/3rdparty/precompiled_headers folder was created -
to use for any future 3rd party components' precompiled headers.

To enable a usage of precompiled headers feature in Qt projects
'precompile_header' has to be added to CONFIG. It is done by default
for limited platforms only (e.g. not for Linux now), so to enable it on
any other platform - e.g. special qmake command has to be used:

qmake "CONFIG *= precompile_header" -r ../../qt-creator/

To disable a usage of precompiled headers (on platforms where it is
pre-enabled - otherwise it will be used automatically):

qmake "CONFIG -= precompile_header" -r ../../qt-creator/

To see on which platforms precompiled headers feature is enabled
by default - qt/mkspecs folder has to be checked.

Precompiled headers require an additional space on the disk, it looks
like for Qt Creator full size of the shadow build folder grows up to
2 times (e.g. 1.5 GB to 3 GB).

Test results:

Linux x64, gcc 4.4, T7500, 3 GB RAM: About 22.5 minutes are reduced
to about 14 minutes (almost 80% faster).

Windows x86, vs2008, P8400, 2 GB RAM: About 70 minutes are reduced
to about 20 minutes (amazing 250% faster).

Merge-request: 2182
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

Reported on IRC
Reviewed-By: hjk

Reviewed-By: Oswald Buddenhagen

use the data copying custom compiler approach here, too.
this leaves more work to qmake, which is good.
on the upside, pluginspecs will be installed when they change without
having force a re-link of the plugin itself.
on the downside, installation of a pluginspec will force a re-link of
the plugin. oh, well - you can't have it all (with qmake) ...

now bin and share are not pegged to linking the executable any more,
but are proper subdirs targets of their own.
unforturnately, qmake is a bit tenacious, so we hack around a bit. :)

more or less in passing by, i removed some superfluous trailing slashes
and added path normalization as well.

Details:  - Somehow CONFIG+=plugin requires a CONFIG+=plugin_with_soname
to correctly link on runtime on Mac.

Details:  Creator on Linux works now in two modes:
          1) out of the build dir (shadow builds to be tested)
          2) make INSTALL_ROOT=/prefix install

Details:  Make install works now, we just have to agree on layout
details and check for mac compatibility.

Also, plugins will carry no version in their filename anymore starting with
this commit. Versioning happens in the creators pluginloader using the pluginspec file.

Fixed the build system. Generate the object files for release and debug builds in different directories.