Do not rely on dicts.merge to change target
Also make dicts.merge actually not touch target. This is much cleaner
than modifying in place, especially since we assign the result of the
dicts.merge call to target most of the time anyway.
Patch by: Sverre Rabbelier
tinyMCE.addI18n('en.advimage_dlg',{
tab_general:"General",
tab_appearance:"Appearance",
tab_advanced:"Advanced",
general:"General",
title:"Title",
preview:"Preview",
constrain_proportions:"Constrain proportions",
langdir:"Language direction",
langcode:"Language code",
long_desc:"Long description link",
style:"Style",
classes:"Classes",
ltr:"Left to right",
rtl:"Right to left",
id:"Id",
map:"Image map",
swap_image:"Swap image",
alt_image:"Alternative image",
mouseover:"for mouse over",
mouseout:"for mouse out",
misc:"Miscellaneous",
example_img:"Appearance preview image",
missing_alt:"Are you sure you want to continue without including an Image Description? Without it the image may not be accessible to some users with disabilities, or to those using a text browser, or browsing the Web with images turned off.",
dialog_title:"Insert/edit image",
src:"Image URL",
alt:"Image description",
list:"Image list",
border:"Border",
dimensions:"Dimensions",
vspace:"Vertical space",
hspace:"Horizontal space",
align:"Alignment",
align_baseline:"Baseline",
align_top:"Top",
align_middle:"Middle",
align_bottom:"Bottom",
align_texttop:"Text top",
align_textbottom:"Text bottom",
align_left:"Left",
align_right:"Right",
image_list:"Image list"
});