Adding icons in the FT diagram

.idea/misc.xml

src/main/java/ui/avatarbd/AvatarBDBlock.java

src/main/java/ui/ftd/FTDConstraint.java

src/main/java/ui/util/IconManager.java

src/main/java/ui/window/JDialogConstraintText.java

src/main/resources/ui/util/AfterFT.png

src/main/resources/ui/util/AndFT.png

src/main/resources/ui/util/BeforeFT.png

src/main/resources/ui/util/NotFT.png

src/main/resources/ui/util/SequenceFT.png