FMSLogo Code

Add more test variations for ` based on recent updates to its documentation.

Note that bug #574 (a doc update) has been fixed in 8.2.0.

Fix bug #574; Clarify how nesting backquotes works.
Also improve the examples by adding a new one with a detailed explanation and remove ones which don't illuminate.

Fix bug #575; "las otras símbolos" -> "los otros símbolos"

Indent the body less.
This gives more space for the code listings in the Example sections.

Fix a syntax error in a comment.

Set variablelist.as.blocks=1 to give examples more width before being truncated in PDF.

Delete the copy of the English manual which was set aside for translating into Hindi.
If that does ever happen, it should start from a recent copy, not this old one.

Add missing LOCAL calls to fix leaked global variables

Cleanup: Remove input_blocking and iblk_buf
These variables and the related logic aren't needed in FMSLogo, since it doesn't read from stdin.