[23499] Bug 627575 - Stylesheet names with non-alphanumeric characters and saved-reports

g_key_file_[gs]et_string parses the string to escape newlines and comments
This erroneously does some escaping in the #{symbol name}# guile extended format
for symbols. Since we already strip newlines and comments ourselves,
we can save and store the string without any additional parsing
using g_key_file_[gs]et_value.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/branches/2.4@23500 57a11ea4-9604-0410-9ed3-97b8803252fd