lineedit: first shot at optional unicode bidi input support

lineedit: first shot at optional unicode bidi input support

function                                             old     new   delta
read_line_input                                     4886    5003    +117
in_uint16_table                                        -      97     +97
in_interval_table                                      -      78     +78
static.rtl_b                                           -      68     +68
unicode_isrtl                                          -      55     +55
isrtl_str                                              -      51     +51
static.rtl_p                                           -      42     +42
unicode_conv_to_printable2                           633     477    -156
------------------------------------------------------------------------------
(add/remove: 6/0 grow/shrink: 1/1 up/down: 508/-156)          Total: 352 bytes

Signed-off-by: Tomas Heinrich <heinrich.tomas@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>