The "use block caret" IDEA option controls the style of the cursor: when
it's enabled, the cursor is drawn as a block, and when it's disabled,
it's drawn as a bar. However, after installing IdeaVIM, this option
isn't respected; the plugin always uses a block cursor when in command
mode, and always uses a bar cursor when in insert mode.
This commit changes the behavior so that when the "use block caret"
option is enabled, IdeaVIM's insert mode uses a block cursor instead of
a bar cursor. The cursor in normal mode is always drawn as a block
cursor. If the "use block caret" option is disabled, the behavior is the
same as in previous versions of IdeaVIM (block cursor in normal mode,
bar cursor in insert mode).
Fixes VIM-1475 (on YouTrack)
