Few changes to allow the support of right to left languages

[AmrBarghouthi]

This to makes it possible to flip the image in RecolorImage which is needed for some icons when translating Apps to support Right to Left languages

[AmrBarghouthi]

I added a function to indicate the language direction to be used in QML files
example use is adding the following to row layout elements parent

LayoutMirroring.enabled: catalog.i18nIsRightToLeft()
LayoutMirroring.childrenInherit: true

[Ghostkeeper]

I'm a bit confused as to why you would want to mirror images in right-to-left scripts?

And the solution of adding a translated string may not be very robust either. It would be better to get this from the metadata of the translation. I think gettext.info() can read that.

[AmrBarghouthi]

@GhostKeep image mirroring is going to be for stuff like arrows

as for metadata of the translation I will look into it

[AmrBarghouthi]

I update it the i18nIsRightToLeft function to get the direction from language metadata
thanks @Ghostkeeper for the suggestion

[Ghostkeeper]

The only directional arrows that we have are really the folding arrows in the setting category headers. But those are not really related to any text, are they?

[AmrBarghouthi]

yes but it's not only for arrows
for example

these icons look way better when mirrored in right to left application
anyway it is a feature of Uranium that doesn't really do any harm if added

[Ghostkeeper]

I'll change this to layer.enabled: mirror to save some rendering performance. These images are used a lot (e.g. with every setting) so performance is important.

[Ghostkeeper]

I can't seem to be able to get this to work.

I added this property to the Dutch translation .po files (all 4):

"Language-Direction: rtl\n"

Alternatively I also tried without the newline and space, in case that mattered (though I think Gettext filters that out):

"Language-Direction:rtl"

I then recompiled the .po files to .mo files and printed the isRightToLeft() function from QML:

print(catalog.i18nIsRightToLeft());

However it still returns qml: false.

Setting the mirror property works, but setting it to depend on being right-to-left never mirrors the image.