Visual plugin: SPHINCS+ fixes

[simlei]

Original issue: #287 (comment)

• Prio Medium/high: visualizations are broken under Linux and would confuse the user.

• Medium: context help

• The visualizations on linux are broken, s. I1). Sphincs without the plus seems to not have these problems with the same kind of visualization. Fix: remove thread and replace it with suitable SWT idioms for tracking scrolling, dragging

• text field below description in I2) has no content, I am not sure what it does.

• see: SPHINCS+ CPU load #258

• see: SPHINCS visualization misbehaves #270

Textual:

• Online Help:
  • below the first "remark" there is a solitary dot. remove.

I1)

I2)

[simlei]

The problem visible in I1) seem not fixable under linux.

crypto/org.jcryptool.visual.sphincsplus/src/org/jcryptool/visual/sphincsplus/ui/SphincsPlusForsView.java

Lines 131 to 132 in 4d0070a

	GraphContainer container_1 = new GraphContainer(graph, SWT.NONE, "ROOT-Node");
	GraphContainer container_2 = new GraphContainer(graph, SWT.NONE, "ROOT-Node");

with only the first line, it works. with both lines, SWT crashes, complaining about a color being disposed. No involvement of any org.jcryptool code, so I see this as a bug in the ZEST graph framework.

The graph nests another graph in a container, the GraphContainer instance -- this is unique in our code base (Huffman coding has a good ZEST visualization but not with this detail).

Possible solutions:

1. remove visualization.
2. keep visualization, but replace container with a more standard means of drawing the graph. Idea: replace containers with a single node and upon selection, show inner graph in a widget on the right.

[simlei]

background threads were removed in 4d0070a but the cpu load seems to be high still under linux. it is entirely possible that the ZEST visualization as it contains error is constantly trying to log these on redraw into the error log and the cascading problems with that cause this high load. Will have to try under windows, but only after graph revamp or removal.

[simlei]

Preliminary solution for this plugin is in branch https://github.com/jcryptool/crypto/tree/i300_sphincsplus_graphrework but it will have to sit there for a while until completion (3rd tab not changed at all yet), I'll get around to it in ca. 2 weeks.