fix lib extension and remove default mcvcr80 runtime for MinGW
added some clarification to the installer batch file help text
more clarification of help text
added comments in th installer, added slightly more verbose output during installing, and fixed the bug of MinGW binaries being overwritten.
added user instructions for updating path variables
moved some blocks around to make it more logical
Updated installer batch file
library name to link against is now configurable, and a default list to look for is set
Library and runtime will be written into the config files now
/L can no longer be used with /LUA /INC /BIN /LIB (will error and exit)
More verbose output while searching for a Lua installation
installer bugfix in case of quoted arguments for paths
fixed installer: typo in write config file
Accept rocks and rockspecs in the remove command: interpret rock name and version from their names.
Fix crash in the 'show' command when using a table as entry in rocks_trees config file.
Improve diagnostics on error copying 'lua' directory.
Actually it would be better to check if this is really working as intended.
Merge pull request #113 from Tieske/MinGW_fix

Mingw fix and windows installer batch file updated
small fix to installer, for consistency (no functional impact)