[Kst] Kst 2.0 Install and Settings locations

[Mike Fenton]

As per previous conversations / bug reports in the former Kst2 List I
want to move the discussion here and outline the current desired layouts.

Settings:

Rather than write directly to an Ini file which then must be located
relative to the binary, Kst will make use of the QSettings objects
ability to properly place the settings in the UserScope in the
appropriate location depending on the system.  Settings in OpenSUSE are
stored in ~/.config/kst, and in Windows in the registry.

ASCII settings - Settings will be added to provide global settings for
ascii and these will be configurable using a flag on the ascii
configuration dialog.  These global settings will be used anytime a new
ascii file is opened, re-opening a specific ascii file will use the
settings configured on the last time that particular file was opened.

File Locations on Install

Note:  This change will only affect linux, Windows/Mac will not be changed.

The install location will be configurable using the environment variable
INSTALL_PREFIX, and will default to /usr
Library install location will be configurable using the environment
variable INSTALL_LIBDIR and will default to lib
Plugins will now be installed to INSTALL_PREFIX / INSTALL_LIBDIR / kst

It will also be possible to continue to run Kst from the build lcoation
without calling make install as the configured path will be provided as
an extra location to search and previous search paths will remain.

Thoughts and comments are welcome,
Mike