Bug 737583 - Fix static placement of Chinese IME window

Call gtk_im_context_set_cursor_location() whenever we draw the text
tool cursor or start a preedit sequence.
Bug 736232 - Strange result using transparent layer, blending modes...

...and layer opacity

Use a temporary variable to store intermediate result instead of
writting 2 times to the output buffer, because input and output
buffer might be the same.
file-bmp: Fix final bfSize patched into BMP header (#737669)
file-bmp: Use cleaner serialization (sign)
plug-ins: port file-header to GIO
plug-ins: rename output_printf() to simply print() in file header
Clean up code around calls to g_file_replace()

- use G_FILE_CREATE_NONE instead of 0
- don't put "Could not open <file> for writing: <error>" around the
  returned error, the returned message is already verbose
plug-ins: merge 4 entry callbacks into one in file-html-table

And some general cleanup.
plug-ins: port file-html-table to GIO
plug-ins: remove obsolete includes from file-html-table
plug-ins: port file-xbm-save to GIO
plug-ins: 64bit double saving support for file-fits

Quickly hacked up, loads again using the plug-in.
libgimpbase: GimpAttributes sorting; Plug-ins: attributes fixed for new sorting.
Since GHashTable does not sort keys, a GList was necessary for sorting purposes.
But plain string sorting is not enough for structured tags, when I got an image
with 176(!) xmpMM.History elements. In string sorting, after 10 comes 100, so an
enhanced sorting was necessary.
modules: plug leak in color-selector-cmyk

Don't leak the RGB profile if the CMYK profile can't be loaded
libgimpwidgets: don't leak the empty_iter in GimpIntStore
libgimpmodule: disconnect from the modules' "modified" signal

when GimpModuleDB is finalized.
libgimpconfig: don't leak "expanded" in gimp_config_path_expand_to_files()
app: don't leak the gimpdir GFile in app_run()
app: don't leak all results from separate_uline_pattern() in GimpSpinScale
app: don't leak "buffer" in gimp_interpreter_db_add_binfmt_misc()