Fix bug with syntax coloring and anchor ^

Anchor ^ is used "to indicate that the keyword can only appear at the
front of a line (after optional whitespace but no printed characters)".

If a such anchored keyword is preceded by nothing but other keywords
and whitespace, it is handled as if nothing had been appeared before it.

Example:

  if gui == "termcap"

Although the equal sign and the quotation mark are defined "anchor ^",
they will be colored as keyword resp. comment.

Fix it by noting the end of indentation when a keyword has been
detected.
Update syntax description for icewm/preferences
Complete documentation

Add a missing information.
Improve bottom row coloring of windows without input focus

The bottom row of a window that currently doesn't have the input focus
is colored in the idle color. The ruler and the label for the current
parse state, however, are unaffected and retain their colors.

In order to have the bottom row completely colored in the idle color,
change the colors of the ruler and the label according to whether the
window has input focus or not.
Add missing initialization

'str' may be used uninitialized if terminal has :me: but no :mr:
Fix condition always evaluating as 'true'

It seems likely to be a typo.