Detect mixed tabs and spaces

Whitespace highlighting in error color is very useful since .pfw files are
not supporting spaces. Only tabs are allowed.
However, the whitespace highlighting was incomplete, since it did not
detect mixed indentations, such as <Tab><Space> and <Space><Tab>.

This patch updates whitespace detection highlight to take into
account those cases which fixes #2.

Signed-off-by: Mattijs Korpershoek <mattijs.korpershoek@gmail.com>
Update component matching regexp with NmToken definition

According to the .xsd definition of parameter-framework/core/Schemas,
components name respect the XML definition of XS:NMTOKEN. See
http://www.w3.org/TR/2000/WD-xml-2e-20000814#NT-Nmtoken for additional
information about this definition.

This patch updates the component regexp to detect component names the same
way as the schemas from the parameter-framework would do.
It fixes #5.

Signed-off-by: Mattijs Korpershoek <mattijs.korpershoek@gmail.com>
Remove criteria value higlighting

Some specific values such as True,False and none were highlighting as
CriteriaValues. This makes sense if every criteria value could be
highlighting.
However, those values are user-defined and not known in advance.
It has no sense to partially highlight them, so the support should be
removed.

This patch removes the support for partial CriteriaValues highlight for
a more consistent behavior.
It fixes #3.

Signed-off-by: Mattijs Korpershoek <mattijs.korpershoek@gmail.com>