Add more Preedit enumerations for custom styles

Add more Preedit enumerations for custom styles

- Add more preedit styles for substring : CUSTOM_PLATFORM_STYLE_1 ~ 4
- The preedit type is NONE, SUB1 ~ SUB7.
   But, DALi changed the name exactly, such as 'UNDERLINE' instead of 'SUB1' and
  'REVERSE' instead of 'SUB2'.
   CUSTOM_PLATFORM_STYLE_1 ~ 4 are just to draw the text in underline
  with various background color.

- The index received from imf is a byte. So, it should be converted to character index.

Change-Id: Iea64e1bfc27ff291cee592c839013171df75d31c
Signed-off-by: Seoyeon Kim <seoyeon2.kim@samsung.com>