[Robustness] use backslash when sourcing in case of overridden dot

Fixes #1278.

README.markdown

@@ -74,7 +74,7 @@ wget -qO- https://raw.githubusercontent.com/creationix/nvm/v0.32.1/install.sh |
 
 ```sh
 export NVM_DIR="$HOME/.nvm"
-[ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh" # This loads nvm
+[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh" # This loads nvm
 ```
 
 You can customize the install source, directory, profile, and version using the `NVM_SOURCE`, `NVM_DIR`, `PROFILE`, and `NODE_VERSION` variables.
@@ -124,7 +124,7 @@ Add these lines to your `~/.bashrc`, `~/.profile`, or `~/.zshrc` file to have it
 
 ```sh
 export NVM_DIR="$HOME/.nvm"
-[ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh" # This loads nvm
+[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh" # This loads nvm
 ```
 
 ### Manual upgrade

install.sh

@@ -297,7 +297,7 @@ nvm_do_install() {
   local INSTALL_DIR
   INSTALL_DIR="$(nvm_install_dir)"
 
-  SOURCE_STR="\nexport NVM_DIR=\"$INSTALL_DIR\"\n[ -s \"\$NVM_DIR/nvm.sh\" ] && . \"\$NVM_DIR/nvm.sh\"  # This loads nvm\n"
+  SOURCE_STR="\nexport NVM_DIR=\"$INSTALL_DIR\"\n[ -s \"\$NVM_DIR/nvm.sh\" ] && \\. \"\$NVM_DIR/nvm.sh\"  # This loads nvm\n"
 
   if [ -z "${NVM_PROFILE-}" ] ; then
     echo "=> Profile not found. Tried ${NVM_PROFILE} (as defined in \$PROFILE), ~/.bashrc, ~/.bash_profile, ~/.zshrc, and ~/.profile."