Fix troff warnings in manpages

[davidpolverari]

Hi James! While packaging voacapl for Debian, its package checker (lintian) found some warnings caused by voacap manpages:

• troff does not allow newline characters in an escape name.
• it treats lines starting with an apostrophe as a control line, that can be followed by a macro call.

This patch, in the case you merge it, replaces lines containing \n by .br, and uses \(aq instead of apostrophes on the beginning of a line.

The warnings emitted by troff can be seen using the following command:

LC_ALL=C.UTF-8 MANROFFSEQ='' MANWIDTH=80 \
	man --warnings -E UTF-8 -l -Tutf8 -Z man/voacapl.1 > /dev/null