gendoc: automatically create help for default extensions.
Adds a section in the hg.1 manpage and corresponding hg.1.html
file. Each extension is listed with its module docstring, followed by
the commands defined by that extendsion.
Creates help for extensions by extracting doc strings from the extension modules
and its commands.
A = 'data/aux.bla/bla.aux/prn/PRN/lpt/com3/nul/coma/foo.NUL/normal.c.i'
B = 'data/au~78.bla/bla.aux/pr~6e/_p_r_n/lpt/co~6d3/nu~6c/coma/foo._n_u_l/normal.c.i'
A = 'data/AUX/SECOND/X.PRN/FOURTH/FI:FTH/SIXTH/SEVENTH/EIGHTH/NINETH/TENTH/ELEVENTH/LOREMIPSUM.TXT.i'
B = 'dh/au~78/second/x.prn/fourth/fi~3afth/sixth/seventh/eighth/nineth/tenth/loremia20419e358ddff1bf8751e38288aff1d7c32ec05.i'
A = 'data/enterprise/openesbaddons/contrib-imola/corba-bc/netbeansplugin/wsdlExtension/src/main/java/META-INF/services/org.netbeans.modules.xml.wsdl.bindingsupport.spi.ExtensibilityElementTemplateProvider.i'
B = 'dh/enterpri/openesba/contrib-/corba-bc/netbeans/wsdlexte/src/main/java/org.net7018f27961fdf338a598a40c4683429e7ffb9743.i'
A = 'data/AUX.THE-QUICK-BROWN-FOX-JU:MPS-OVER-THE-LAZY-DOG-THE-QUICK-BROWN-FOX-JUMPS-OVER-THE-LAZY-DOG.TXT.i'
B = 'dh/au~78.the-quick-brown-fox-ju~3amps-over-the-lazy-dog-the-quick-brown-fox-jud4dcadd033000ab2b26eb66bae1906bcb15d4a70.i'
A = 'data/Project Planning/Resources/AnotherLongDirectoryName/Followedbyanother/AndAnother/AndThenAnExtremelyLongFileName.txt'
B = 'dh/project_/resource/anotherl/followed/andanoth/andthenanextremelylongfilenaf93030515d9849cfdca52937c2204d19f83913e5.txt'
A = 'data/Project.Planning/Resources/AnotherLongDirectoryName/Followedbyanother/AndAnother/AndThenAnExtremelyLongFileName.txt'
B = 'dh/project_/resource/anotherl/followed/andanoth/andthenanextremelylongfilena0fd7c506f5c9d58204444fc67e9499006bd2d445.txt'
A = 'data/foo.../foo / /a./_. /__/.x../ bla/.FOO/something.i'
B = 'data/foo..~2e/foo ~20/~20/a~2e/__.~20/____/~2ex.~2e/~20 bla/~2e_f_o_o/something.i'